Metal packaging powder coating compositions, coated metal substrates, and methods

ABSTRACT

Powder coating compositions, particularly metal packaging powder coating compositions, coated metal substrates, and methods; wherein the powder coating compositions include powder polymer particles comprising a polymer having a number average molecular weight of at least 2000 Daltons, wherein the powder polymer particles have a particle size distribution having a D50 of less than 25 microns; and, in certain embodiments, one or more charge control agents in contact with the powder polymer particles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.17/097,929, filed Nov. 13, 2020, which claims the benefit of U.S.Provisional Application Ser. No. 62/935,404, filed Nov. 14, 2019, andU.S. Provisional Application Ser. No. 63/056,472, filed Jul. 24, 2020,each of which are incorporated herein by reference in their entireties.

BACKGROUND

A wide variety of liquid applied coating compositions have been used toprovide hardened coatings on the surfaces of metal packaging articles(e.g., food and beverage cans, metal closures). For example, metal cansare sometimes coated with liquid coating compositions using “coilcoating” or “sheet coating” operations, i.e., a planar coil or sheet ofa suitable substrate (e.g., steel or aluminum metal) is coated with asuitable liquid coating composition, which is subsequently hardened(e.g., cured). The coated substrate then is formed into the can end orbody. Alternatively, liquid coating compositions may be applied (e.g.,by spraying, dipping, rolling, etc.) to the formed article and thenhardened (e.g., cured) to form a continuous coating.

Metal packaging coatings should preferably be capable of high-speedapplication to the substrate and provide the necessary properties whenhardened to perform in this demanding end use. For example, the hardenedcoating should preferably be safe for food contact, not adversely affectthe taste of the packaged food or beverage product, have excellentadhesion to the substrate, resist staining and other coating defectssuch as “popping,” “blushing” and/or “blistering,” and resistdegradation over long periods of time, even when exposed to harshenvironments. In addition, the hardened coating should generally becapable of maintaining suitable film integrity during can fabricationand be capable of withstanding the processing conditions to which thecan may be subjected during product packaging. The hardened coatingshould also generally be capable of surviving routine can drop events(e.g., from a store shelf) in which the underlying metal substrate isdented, without rupturing or cracking.

Liquid packaging coatings largely satisfy the needs of the rigid metalpackaging market today, but there are some notable disadvantagesassociated with their use. Liquid coatings contain large volumes ofwater and/or organic solvents that contribute to shipping costs. Then asthe liquid coating composition is applied, a significant amount ofenergy must be expended, often in the form of burning fossil fuels, toremove the water or solvent during the coating hardening process. Onceorganic solvent is driven out of the hardening film, it eithercontributes to Volatile Organic Content (VOC) generation or it must bemitigated by large, energy-consuming, thermal oxidizers. Additionally,these processes can emit significant volumes of carbon dioxide.

One alternative to conventional liquid packaging coatings is the use oflaminate coatings. In this process, a laminated or extruded plastic filmis adhered to the metal via a heating step. The product is a coatedmetal substrate that can then be used to produce various food andbeverage can parts. The process required to produce laminate films isonly compatible with a limited number of thermoplastic materials (e.g.,the materials must have the tensile strength required to be stretchedinto thin films). There is also a limit on the extent to which suchfilms can be stretched, restricting how thin the final coating can beapplied on the substrate. There can also be a significant capitalinvestment required to retrofit an existing can-making line to acceptlaminated steel or aluminum.

Another alternative, powder coating, has seen narrow utility in rigidmetal packaging (e.g., powdered side seam stripes for welded canbodies). Its use is limited, however, because the relatively largeparticle size of traditionally ground powders (greater than 30 microns)is not amenable to the low film thickness required for packagingcoatings (typically less than 10 microns).

Although smaller particles (e.g., 5 microns) can be formed usinggrinding/milling techniques, the low molecular weights of thesepolymeric materials (a limitation of the properties required for suchintense grinding) are not believed to be amenable to forming filmshaving the performance standards required of metal packaging coatingsneeded in the food and beverage industry.

There are methods available to produce finer particle sizes other thanmechanical methods such as grinding (i.e., chemically produced powders),but traditional powder application of such fine powders often results ininconsistent or otherwise low-quality films.

What is needed is an improved coating composition for rigid metalpackaging applications, which overcomes the above disadvantagesassociated with conventional liquid, powder, and laminate packagingcoating compositions.

SUMMARY

The present disclosure provides powder coating compositions,particularly metal packaging (e.g., a food, beverage, aerosol, orgeneral packaging container (e.g., can), portion thereof, or a metalclosure) powder coating compositions, coated metal substrates, andmethods—method of making a metal packaging powder coating composition,method of coating a metal substrate, and method of making a metalpackaging container (e.g., a food, beverage, or aerosol can), a portionthereof, or a metal closure for a container.

In one embodiment, a metal packaging powder coating composition (i.e., acoating composition in the form of a free-flowing powder) is provided.The powder coating composition includes: powder polymer particlescomprising a polymer having a number average molecular weight of atleast 2000 Daltons, wherein the powder polymer particles have a particlesize distribution having a D50 of less than 25 microns; and one or morecharge control agents in contact with the powder polymer particles.

The powder polymer particles are preferably chemically produced.Preferably, the powder polymer particles are not mechanically produced,e.g., ground polymer particles or polymer particles formed from othersimilar fracturing or pulverization processes. More preferably, thepowder polymer particles are spray dried powder particles.

In one embodiment, a method of making a metal packaging powder coatingcomposition is provided. The method includes: providing powder polymerparticles comprising a polymer having a number average molecular weightof at least 2000 Daltons; wherein the powder polymer particles have aparticle size distribution having a D50 of less than 25 microns; andapplying one or more charge control agents to the powder polymerparticles and forming a powder coating composition; wherein the powdercoating composition is a metal packaging coating composition.

In one embodiment, a method of coating a metal substrate suitable foruse in forming metal packaging (e.g., a container such as a food,beverage, or aerosol container, a portion thereof, or a metal closure)is provided. The method includes: providing a metal packaging powdercoating composition, wherein the powder coating composition comprisespowder polymer particles including a polymer having a number averagemolecular weight of at least 2000 Daltons, wherein the powder polymerparticles have a particle size distribution having a D50 of less than 25microns; directing the powder coating composition to at least a portionof the metal substrate, wherein the metal substrate has an averagethickness of up to 635 microns; and providing conditions effective forthe powder coating composition to form a hardened continuous adherentcoating on at least a portion of the metal substrate, wherein thehardened continuous adherent coating has an average thickness of up to100 microns (preferably up to 50 microns, more preferably up to 25microns, even more preferably up to 20 microns, still more preferably upto 15 microns, and most preferably up to 10 microns).

In one embodiment, a coated metal substrate including a metal substratehaving a hardened continuous adherent coating disposed on at least aportion of a surface thereof is provided, wherein: the metal substratehas an average thickness of up to 635 microns; the hardened continuousadherent coating has an average thickness of up to 100 microns(preferably up to 50 microns, more preferably up to 25 microns, evenmore preferably up to 20 microns, still more preferably up to 15microns, and most preferably up to 10 microns); and the hardenedcontinuous adherent coating is formed from a metal packaging powdercoating composition. Such powder coating composition includes: powderpolymer particles including a polymer having a number average molecularweight of at least 2000 Daltons, wherein the powder polymer particleshave a particle size distribution having a D50 of less than 25 microns;and preferably a lubricant.

In one embodiment, a method of making metal packaging (e.g., a containersuch as a food, beverage, aerosol, or general packaging container, aportion thereof, or a metal closure, which may be used for a metalcontainer or container of other materials, e.g., glass) is provided. Themethod includes: providing a metal substrate having a hardenedcontinuous adherent coating disposed on at least a portion of a surfacethereof; and forming the substrate into at least a portion of a metalpackaging container, a portion thereof, or a metal closure. The metalsubstrate has an average thickness of up to 635 microns. The hardenedcontinuous adherent coating is formed from a metal packaging powdercoating composition; wherein the powder coating composition preferablyincludes a lubricant and powder polymer particles, wherein the powderpolymer particles comprise a polymer having a number average molecularweight of at least 2000 Daltons, and wherein the powder polymerparticles have a particle size distribution having a D50 of less than 25microns.

Herein, “metal packaging” coating compositions refer to coatingcompositions that are suitable for coating on rigid metal directly (asopposed to, e.g., a free-standing plastic film of at least 10 micronsthick, paper or other fibrous material, or metal foil, which is thenapplied (e.g., adhered) to rigid metal packaging), or indirectly on apre-treatment layer or a primer layer that is not derived from afree-standing film (i.e., a film formed before being applied to anothersubstrate, such as by lamination) overlying a substrate. Thus, by way ofexample, a powder coating composition applied either to a paper layeroverlying a metal substrate, or to a laminated plastic layer overlying ametal substrate, is not a metal packaging coating composition as usedherein.

The particle size may be determined by laser diffraction particle sizeanalysis for starting materials (e.g., primary polymer particles, chargecontrol agents, lubricants, etc.), using a Beckman Coulter LS 230 LaserDiffraction Particle Size Analyzer or equivalent, calibrated asrecommended by the manufacturer. The particle size of the polymeragglomerates and powder polymer compositions may be determined by laserdiffraction particle size analysis, or by dynamic image analysis (DIA),which measures size (as well as other parameters) based on particleimages, according to, e.g., ISO 13322-2 (2006) test method, using aCAMSIZER X2 device (Retsch Technology GmbH, Haan, Germany) equipped withthe X-Jet plug-in cartridge and its related software, according todevice manufacturer's recommendations. Alternatively, differentialmobility analysis (DMA), followed by detection using an aerodynamicparticle spectrometer (APS) or optical particle spectrometer (OPS) (J.Phys. Chem. B, 2009, 113, 970-976), may be used to determine particlesize distribution of starting materials, polymer agglomerates, or powderpolymer compositions.

The D-values—D50, D90, D95, and D99—are the particle sizes which dividea sample's volume into a specified percentage when the particles arearranged on an ascending particle size basis. For example, for particlesize distributions the median is called the D50 (or ×50 when followingcertain ISO guidelines). The D50 is the particle size in microns thatsplits the distribution with half above and half below this diameter.The Dv50 (or Dv0.5) is the median for a volume distribution. The D90describes the particle size where ninety percent of the distribution hasa smaller particle size and ten percent has a larger particle size. TheD95 describes the particle size where ninety five percent of thedistribution has a smaller particle size and five percent has a largerparticle size. The D99 describes the particle size where ninety ninepercent of the distribution has a smaller particle size and one percenthas a larger particle size. Unless specified otherwise herein, D50, D90,D95, and D99 refer to D_(v)50, D_(v)90, D_(v)95, and D_(v)99,respectively. The D-values specified herein may be determined by laserdiffraction particle size analysis, DIA, or DMA.

A “powder coating composition” refers to a composition that includespowder particles and does not include a liquid carrier, although it mayinclude trace amounts of water or an organic solvent that may have beenused in the preparation of the powder particles. The powder coatingcomposition is typically in the form of a finely divided free-flowingpowder polymer particles, which may or may not be in the form ofagglomerates.

Herein, an agglomerate (or cluster) is an assembly of particles, thelatter of which are referred to as primary particles.

A “hardened” coating refers to one wherein particles are covalentlycured via a crosslinking reaction (e.g., a thermoset coating) or simplyfused into a continuous layer in the absence of a crosslinking reaction(e.g., a thermoplastic coating), and adhered to a metal substrate,thereby forming a coated metal substrate. The term “hardened” does notimply anything related to the relative hardness or softness (Tg) of acoating.

An “adherent” coating refers to a hardened coating that adheres to asubstrate, such as a metal substrate, according to the Adhesion Testdescribed in the Examples Section. An adhesion rating of 9 or 10,preferably 10, is considered to be adherent.

A “continuous” coating refers to a hardened coating that is free ofpinholes and other coating defects that result in exposed substrate.Such film imperfections/failures can be indicated by a current flowmeasured in milliamps (mA) using the Flat Panel Continuity Testdescribed in the Examples Section.

The term “substantially free” of a particular component means that thecompositions or hardened coatings of the present disclosure contain lessthan 1,000 parts per million (ppm) of the recited component, if any. Theterm “essentially free” of a particular component means that thecompositions or hardened coatings of the present disclosure contain lessthan 100 parts per million (ppm) of the recited component, if any. Theterm “essentially completely free” of a particular component means thatthe compositions or hardened coatings of the present disclosure containless than 10 parts per million (ppm) of the recited component, if any.The term “completely free” of a particular component means that thecompositions or hardened coatings of the present disclosure contain lessthan 20 parts per billion (ppb) of the recited component, if any.

The term “bisphenol” refers to a polyhydric polyphenol having twophenylene groups that each include six-carbon rings and a hydroxyl groupattached to a carbon atom of the ring, wherein the rings of the twophenylene groups do not share any atoms in common. By way of example,hydroquinone, resorcinol, catechol, and the like are not bisphenolsbecause these phenol compounds only include one phenylene ring.

The term “food-contact surface” refers to a surface of an article (e.g.,a food or beverage can) intended for prolonged contact with foodproduct. When used, for example, in the context of a metal substrate ofa food or beverage container (e.g., can), the term generally refers toan interior metal surface of the container that would be expected tocontact food product in the absence of powder coating compositionapplied thereon. By way of example, a base layer, intermediate layer,and/or polymer top-coat layer applied on an interior surface of a metalfood or beverage can is considered to be applied on a food-contactsurface of the can.

The term “on,” when used in the context of a coating applied on asurface or substrate, includes both coatings applied directly (e.g.,virgin metal or pre-treated metal such as electroplated steel) orindirectly (e.g., on a primer layer) to the surface or substrate. Thus,for example, a coating applied to a pre-treatment layer (e.g., formedfrom a chrome or chrome-free pretreatment) or a primer layer overlying asubstrate constitutes a coating applied on (or disposed on) thesubstrate.

The terms “polymer” and “polymeric material” include, but are notlimited to, organic homopolymers, copolymers, such as for example,block, graft, random and alternating copolymers, terpolymers, etc., andblends and modifications thereof. Furthermore, unless otherwisespecifically limited, the term “polymer” shall include all possiblegeometrical configurations of the material. These configurationsinclude, but are not limited to, isotactic, syndiotactic, and atacticsymmetries.

The term “aryl group” (e.g., an arylene group) refers to a closedaromatic ring or ring system such as phenylene, naphthylene,biphenylene, fluorenylene, and indenyl, as well as heteroarylene groups(e.g., a closed aromatic or aromatic-like ring hydrocarbon or ringsystem in which one or more of the atoms in the ring is an element otherthan carbon (e.g., nitrogen, oxygen, sulfur, etc.)). Suitable heteroarylgroups include furyl, thienyl, pyridyl, quinolinyl, isoquinolinyl,indolyl, isoindolyl, triazolyl, pyrrolyl, tetrazolyl, imidazolyl,pyrazolyl, oxazolyl, thiazolyl, benzofuranyl, benzothiophenyl,carbazolyl, benzoxazolyl, pyrimidinyl, benzimidazolyl, quinoxalinyl,benzothiazolyl, naphthyridinyl, isoxazolyl, isothiazolyl, purinyl,quinazolinyl, pyrazinyl, 1-oxidopyridyl, pyridazinyl, triazinyl,tetrazinyl, oxadiazolyl, thiadiazolyl, and so on. When such groups aredivalent, they are typically referred to as “arylene” or “heteroarylene”groups (e.g., furylene, pyridylene, etc.).

The term “phenylene” as used herein refers to a six-carbon atom arylring (e.g., as in a benzene group) that can have any substituent groups(including, e.g., halogens, hydrocarbon groups, oxygen atoms, hydroxylgroups, etc.). Thus, for example, the following aryl groups are eachphenylene rings: —C₆H₄—, —C₆H₃(CH₃)—, and —C₆H(CH₃)₂Cl—. In addition,for example, each of the aryl rings of a naphthalene group are phenylenerings.

Herein, the term “comprises” and variations thereof do not have alimiting meaning where these terms appear in the description andembodiments. Such terms will be understood to imply the inclusion of astated step or element or group of steps or elements but not theexclusion of any other step or element or group of steps or elements. By“consisting of” is meant including, and limited to, whatever follows thephrase “consisting of.” Thus, the phrase “consisting of” indicates thatthe listed elements are required or mandatory, and that no otherelements may be present. By “consisting essentially of” is meantincluding any elements listed after the phrase, and limited to otherelements that do not interfere with or contribute to the activity oraction specified in the disclosure for the listed elements. Thus, thephrase “consisting essentially of” indicates that the listed elementsare required or mandatory, but that other elements are optional and mayor may not be present depending upon whether or not they materiallyaffect the activity or action of the listed elements. Any of theelements or combinations of elements that are recited in thisspecification in open-ended language (e.g., comprise and derivativesthereof), are considered to additionally be recited in closed-endedlanguage (e.g., consist and derivatives thereof) and in partiallyclosed-ended language (e.g., consist essentially, and derivativesthereof).

The words “preferred” and “preferably” refer to embodiments of thedisclosure that may afford certain benefits, under certaincircumstances. However, other embodiments may also be preferred, underthe same or other circumstances. Furthermore, the recitation of one ormore preferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the disclosure.

In this application, terms such as “a,” “an,” and “the” are not intendedto refer to only a singular entity, but include the general class ofwhich a specific example may be used for illustration. The terms “a,”“an,” and “the” are used interchangeably with the term “at least one.”The phrases “at least one of” and “comprises at least one of” followedby a list refers to any of the items in the list and any combination oftwo or more items in the list.

As used herein, the term “or” is generally employed in its usual senseincluding “and/or” unless the content clearly dictates otherwise.

The term “and/or” means one or all of the listed elements or acombination of any two or more of the listed elements.

Also herein, all numbers are assumed to be modified by the term “about”and in certain embodiments, preferably, by the term “exactly.” As usedherein in connection with a measured quantity, the term “about” refersto that variation in the measured quantity as would be expected by theskilled artisan making the measurement and exercising a level of carecommensurate with the objective of the measurement and the precision ofthe measuring equipment used. Herein, “up to” a number (e.g., up to 50)includes the number (e.g., 50).

Also herein, the recitations of numerical ranges by endpoints includeall numbers subsumed within that range as well as the endpoints (e.g., 1to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.) and any sub-ranges(e.g., 1 to 5 includes 1 to 4, 1 to 3, 2 to 4, etc.).

As used herein, the term “room temperature” refers to a temperature of20° C. to 25° C.

The term “in the range” or “within a range” (and similar statements)includes the endpoints of the stated range.

Reference throughout this specification to “one embodiment,” “anembodiment,” “certain embodiments,” or “some embodiments,” etc., meansthat a particular feature, configuration, composition, or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the disclosure. Thus, the appearances of such phrases invarious places throughout this specification are not necessarilyreferring to the same embodiment of the disclosure. Furthermore, theparticular features, configurations, compositions, or characteristicsmay be combined in any suitable manner in one or more embodiments.

The above summary of the present disclosure is not intended to describeeach disclosed embodiment or every implementation of the presentdisclosure. The description that follows more particularly exemplifiesillustrative embodiments. In several places throughout the application,guidance is provided through lists of examples, which examples may beused in various combinations. In each instance, the recited list servesonly as a representative group and should not be interpreted as anexclusive list. Thus, the scope of the present disclosure should not belimited to the specific illustrative structures described herein, butrather extends at least to the structures described by the language ofthe embodiments, and the equivalents of those structures. Any of theelements that are positively recited in this specification asalternatives may be explicitly included in the embodiments or excludedfrom the embodiments, in any combination as desired. Although varioustheories and possible mechanisms may have been discussed herein, in noevent should such discussions serve to limit the subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a scanning electron microscope (SEM) image of conventionalmilled polyester powder coating particles, which are too large and tooangular for use in electromagnetic fields.

FIGS. 1B and 1C are SEMs of chemically produced polymer particles.

FIG. 2 is a schematic of a Spray Drying Apparatus (figure reproducedfrom Büchi B290 spray dryer product literature, BÜCHI Labortechnik AG,Flawil, Switzerland).

FIGS. 3A and 3B are line drawings of an application device capable ofdelivering a powder coating composition to a substrate.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present disclosure provides powder coating compositions (i.e.,coating compositions), particularly metal packaging powder coatingcompositions, coated metal substrates, methods—e.g., method of making ametal packaging powder coating composition, method of coating a metalsubstrate, and method of making metal packaging (e.g., a container, aportion thereof, or a metal closure)—as well as the metal packaging.Examples of metal packaging containers include food, beverage, aerosol,and general metal packaging containers. Examples of metal closuresinclude twist-off caps or lids with threads or lugs and crowns that arecrimped on bottles. Such closures are metal but useful on metal ornon-metal packaging containers.

The metal packaging powder coating compositions are particularly usefulon food-contact surfaces of such metal packaging containers and metalclosures. Although the metal packaging powder coating compositions ofthe present disclosure are particularly useful on a food-contact surfaceof a metal substrate, they may also be useful on other types ofsubstrates for packaging foods, beverages, or other products such asglass (e.g., glass bottles), rigid and flexible plastic, foil, paper,paperboard, or substrates that are a combination thereof.

The resultant coated food-contact surfaces of metal packaging containersand metal closures of the present disclosure are particularly desirablefor packaging liquid-containing products. Packaged products that are atleast partially liquid in nature (e.g., wet) place a substantial burdenon coatings due to intimate chemical contact with the coatings. Suchintimate contact can last for months, or even years. Furthermore, thecoatings may be required to resist pasteurization or cooking processesduring packaging of the product. In the food or beverage packagingrealm, examples of such liquid-containing products include beer,alcoholic ciders, alcoholic mixers, wine, soft drinks, energy drinks,water, water drinks, coffee drinks, tea drinks, juices, meat-basedproducts (e.g., sausages, meat pastes, meat in sauces, fish, mussels,clams, etc.), milk-based products, fruit-based products, vegetable-basedproducts, soups, mustards, pickled products, sauerkraut, mayonnaise,salad dressings, and cooking sauces.

Many coatings that are used to package dry products do not possess thestringent balance of coating properties necessary for use with the above“wet” products. For example, it would not be expected that a coatingused on the interior of a decorative metal tin for individually packagedcookies would exhibit the necessary properties for use as an interiorsoup can coating.

Although containers of the present disclosure may be used to package drypowdered products that tend to be less aggressive in nature towardspackaging coatings (e.g., powdered milk, powdered baby formula, powderedcreamer, powdered coffee, powdered cleaning products, powderedmedicament, etc.), due to the higher volumes in the marketplace, moretypically the coatings will be used in conjunction with more aggressiveproducts that are at least somewhat “wet” in nature. Accordingly,packaging coatings formed from powder coating compositions of thepresent disclosure are preferably capable of prolonged and intimatecontact, including under harsh environmental conditions, with packagedproducts having one or more challenging chemical features, whileprotecting the underlying metal substrate from corrosion and avoidingunsuitable degradation of the packaged product (e.g., unsightly colorchanges or the introduction of odors or off flavors). Examples of suchchallenging chemical features include water, acidity, fats, salts,strong solvents (e.g., in cleaning products, fuel stabilizers, orcertain paint products), aggressive propellants (e.g., aerosolpropellants such as certain dimethyl-ether-containing propellants),staining characteristics (e.g., tomatoes), or combinations thereof.

Accordingly, in certain embodiments, the metal packaging powder coatingcompositions, and preferably, the hardened coatings, of the presentdisclosure are substantially free of each of bisphenol A, bisphenol F,and bisphenol S, structural units derived therefrom, or both. In certainembodiments, the powder coating compositions, and preferably, thehardened coatings, of the present disclosure are essentially free ofeach of bisphenol A, bisphenol F, and bisphenol S, structural unitsderived therefrom, or both. In certain embodiments, the powder coatingcompositions, and preferably, the hardened coatings, of the presentdisclosure are essentially completely free of each of bisphenol A,bisphenol F, and bisphenol S, structural units derived therefrom, orboth. In certain embodiments, the powder coating compositions, andpreferably, the hardened coatings, of the present disclosure arecompletely free of each of bisphenol A, bisphenol F, and bisphenol S,structural units derived therefrom, or both.

In certain embodiments, the metal packaging powder coating compositions,and preferably the hardened coatings, of the present disclosure aresubstantially free of all bisphenol compounds, structural units derivedtherefrom, or both. In certain embodiments, the powder coatingcompositions, and preferably the hardened coatings, of the presentdisclosure are essentially free of all bisphenol compounds, structuralunits derived therefrom, or both. In certain embodiments, the powdercoating compositions, and preferably the hardened coatings, of thepresent disclosure are essentially completely free of all bisphenolcompounds, structural units derived therefrom, or both. In certainembodiments, the powder coating compositions, and preferably thehardened coatings, of the present disclosure are completely free of allbisphenol compounds, structural units derived therefrom, or both.

Preferably, tetramethyl bisphenol F (TMBPF) is not excluded from thepowder coating compositions or hardened coatings of the presentdisclosure. TMBPF is4-[(4-hydroxy-3,5-dimethylphenyl)methyl]-2,6-dimethylphenol, shownbelow, made by the following reaction:

In this context, a “structural unit derived therefrom” is asub-molecular component of any monomeric or polymeric molecule thatderives its structure from the referenced molecule as a result of thereferenced molecule being practically used in the direct synthesisthereof. By way of example, these include aromatic diglycidyl ethercompounds (e.g., diglycidyl ethers of bisphenol (BADGE), diglycidylethers of bisphenol F (BFDGE)), and epoxy novalacs. Furthermore, as usedherein, this term does not include TMBPF (i.e., TMBPF is not derivedfrom bisphenol F).

For example, a powder coating composition is not substantially free ofbisphenol A that includes 600 ppm of bisphenol A and 600 ppm of thediglycidyl ether of bisphenol A (BADGE)—regardless of whether thebisphenol A and BADGE are present in the composition in reacted orunreacted forms, or a combination thereof.

The amount of bisphenol compounds (e.g., bisphenol A, bisphenol F, andbisphenol S) can be determined based on starting ingredients; a testmethod is not necessary and parts per million (ppm) can be used in placeof weight percentages for convenience in view of the small amounts ofthese compounds.

Although intentional addition of bisphenol compounds is generallyundesirable, it should be understood that non-intentional, trace amountsof bisphenols, may potentially be present in compositions or coatings ofthe present application due to, e.g., environmental contamination.

Although the balance of scientific evidence available to date indicatesthat the small trace amounts of these compounds that might be releasedfrom existing coatings does not pose any health risks to humans, thesecompounds are nevertheless perceived by some people as being potentiallyharmful to human health. Consequently, there is a desire by some toeliminate these compounds from coatings on food-contact surfaces.

Also, it is desirable to avoid the use of components that are unsuitablefor such surfaces due to factors such as taste, toxicity, or othergovernment regulatory requirements.

For example, in preferred embodiments, the powder coating composition is“PVC-free.” That is, the powder coating composition preferably contains,if any, less than 2% by weight of vinyl chloride materials and otherhalogenated vinyl materials, more preferably less than 0.5% by weight ofvinyl chloride materials and other halogenated vinyl materials, and evenmore preferably less than 1 ppm of vinyl chloride materials and otherhalogenated vinyl materials, if any.

In certain embodiments, as a general guide to minimize potential, e.g.,taste and toxicity concerns, a hardened coating formed from the powdercoating composition includes, if it includes any detectable amount, lessthan 50 ppm, less than 25 ppm, less than 10 ppm, or less than 1 ppm,extractables, when tested pursuant to the Global Extraction Testdescribed in the Examples Section. An example of these testingconditions is exposure of the hardened coating to 10 wt-% ethanolsolution for two hours at 121° C., followed by exposure for 10 days inthe solution at 40° C.

In some embodiments, such reduced global extraction values may beobtained by limiting the amount of mobile or potentially mobile speciesin the hardened coating. In this context, “mobile” refers to materialthat may be extracted from a cured coating according to the GlobalExtraction Test of the Examples Section. This can be accomplished, forexample, by using pure, rather than impure reactants, avoiding the useof hydrolyzable components or bonds, avoiding or limiting the use of lowmolecular weight additives that may not efficiently react into thecoating, and using optimized cure conditions optionally in combinationwith one or more cure additives. This makes the hardened coatings formedfrom the powder coating compositions described herein particularlydesirable for use on food-contact surfaces.

In certain embodiments, the powder coating composition includes at least50 weight percent (wt-%), at least 60 wt-%, at least 70 wt-%, at least80 wt-%, or at least 90 wt-% of the powder polymer particles, based onthe total weight of the powder coating composition. In certainembodiments, the powder coating composition includes up to 100 wt-%, upto 99.99 wt-%, up to 95 wt-%, or up to 90 wt-%, of the powder polymerparticles, based on the total weight of the powder coating composition.Various optional additives (e.g., charge control agent, lubricant, etc.)can be present in an amount up to 50 wt-%, based on the total weight ofthe powder coating composition.

In certain embodiments, the powder polymer particles are in contact withone or more charge control agents. In certain embodiments, one or morecharge control agents are on a surface of the powder polymer particles.In certain embodiments, one or more charge control agents are adhered toa surface of the powder polymer particles.

In certain embodiments, one or more charge control agents are present inan amount of at least 0.01 weight percent (wt-%), at least 0.1 wt-%, orat least 1 wt-%, based on the total weight of the powder coatingcomposition (e.g., the charge control agent(s) and powder polymerparticles). In certain embodiments, one or more charge control agentsare present in an amount of up to 10 wt-%, up to 9 wt-%, up to 8 wt-%,up to 7 wt-%, up to 6 wt-%, up to 5 wt-%, up to 4 wt-%, or up to 3 wt-%,based on the total weight of the powder coating composition (e.g., thecharge control agent(s) and powder polymer particles).

Preferred powder coating compositions herein are “dry” powder coatingcompositions. That is, the powder particles are not dispersed in aliquid carrier, but rather are present in dry powder form. It should beunderstood, however, that in certain embodiments the dry powder maycontain a de minimis amount of water or organic solvent (e.g., less than2 wt-%, less than 1 wt-%, less than 0.1 wt-%, etc.). Even when subjectedto drying processes, powders will typically include at least someresidual liquid, for example, such as might be present from atmospherichumidity.

Powder Coating Composition and Method of Making

In one embodiment, a metal packaging (e.g., a food, beverage, or aerosolcan) powder coating composition (i.e., a coating composition in the formof a free-flowing powder) is provided. Such compositions can form ahardened adherent coating on a substrate, such as a metal substrate. Inparticular, such compositions may also be useful for coating food,beverage, or aerosol cans, general metal packaging cans or othercontainers, portions thereof, or metal closures for metal packagingcontainers or other containers (e.g., closures for glass jars). Thepowder coating composition includes powder polymer particles andpreferably one or more charge control agents in contact with the powderpolymer particles (e.g., present on, and typically adhered to, surfacesof the powder polymer particles).

Polymer Particles

The molecular weight of the polymer in the powder coating compositionmay be described by a few key metrics given that a typical polymercovers a range of molecular weights. Number average molecular weight(Mn) is determined by dividing the total weight of a sample by the totalnumber of molecules in that sample. Weight average molecular weight (Mw)is determined by calculating the sum of each distinct molecular weightin the sample multiplied by the weight fraction of the sample at thatmolecular weight. Polydispersity index (Mw/Mn) is used to express howbroad the molecular weight range is of the sample. The higher thepolydispersity index, the broader the molecular weight range. The Mn,Mw, and Mw/Mn can all be determined by Gel Permeation Chromatography(GPC), measured against a set of polystyrene standards of varyingmolecular weights.

In certain embodiments, the number average molecular weight (Mn) of thepolymer of the powder particles is at least 2000 Daltons, at least 5,000Daltons, at least 10,000 Daltons, or at least 15,000 Daltons. In certainembodiments, the Mn of the polymer of the powder particles is in themillions (e.g., 10,000,000 Daltons), such as can occur with emulsionpolymerized acrylic polymers or certain other emulsion polymerized latexpolymers, although in certain embodiments the Mn is up to 10,000,000Daltons, up to 1,000,000 Daltons, up to 100,000 Daltons, up to 20,00Daltons. In certain embodiments, the Mn of the polymer of the polymerparticles is at least 2000 Daltons and up to 10,000,000 Daltons, atleast 5000 Daltons and up to 1,000,000 Daltons, at least 10,000 Daltonsand up to 100,000 Daltons, or at least 15,000 Daltons and up to 20,000Daltons.

In certain embodiments, the powder polymer particles are made from apolymer having a polydispersity index (Mw/Mn) of less than 4, less than3, less than 2, or less than 1.5. In certain other embodiments, it maybe advantageous, however, for the polymer to have a polydispersity indexoutside the preceding ranges. For example, without intending to be boundby theory, it may be desirable to have a higher polydispersity index toachieve the benefits of both higher molecular weight (e.g., forflexibility and other mechanic properties) and lower molecular weight(e.g., for flow and leveling) in the same material.

The powder polymer particles have a particle size distribution having aD50 of less than 25 microns, less than 20 microns, less than 15 microns,or less than 10 microns. In certain embodiments, the powder polymerparticles have a particle size distribution having a D90 of less than 25microns, less than 20 microns, less than 15 microns, or less than 10microns. In certain embodiments, the powder polymer particles have aparticle size distribution having a D95 of less than 25 microns, lessthan 20 microns, less than 15 microns, or less than 10 microns. Incertain embodiments, the powder polymer particles have a particle sizedistribution having a D99 of less than 25 microns, less than 20 microns,less than 15 microns, or less than 10 microns.

In certain embodiments, the powder coating composition as a whole (i.e.,all of the particles of the overall powder coating composition or theoverall composition) has a particle size distribution having a D50 ofless than 25 microns, less than 20 microns, less than 15 microns, orless than 10 microns. In certain embodiments, the powder coatingcomposition as a whole has a particle size distribution having a D90 ofless than 25 microns, less than 20 microns, less than 15 microns, orless than 10 microns. In certain embodiments, the powder coatingcomposition as a whole has a particle size distribution having a D95 ofless than 25 microns, less than 20 microns, less than 15 microns, orless than 10 microns. In certain embodiments, the powder coatingcomposition as a whole has a particle size distribution having a D99 ofless than 25 microns, less than 20 microns, less than 15 microns, orless than 10 microns.

The particle size distributions described herein (e.g., D50, D90, D95,D99, etc.) are not restricted on the lower particle size end. In someembodiments, however, the D50 (in certain embodiments, the D90, D95, orD99) may be greater than 1 micron, greater than 2 microns, greater than3 microns, or greater than 4 microns.

The above particle size distributions (e.g., D50, D90, D95, and D99)should be interpreted to factor in any additional materials that mayoptionally be present on the surface of some, or all, of the polymerparticles. Thus, by way of example, if the polymer particles have a D50of 6.5 microns prior to application of an optional charge control agent,and a D50 of 7 microns after application of the optional charge controlagent, as well as in the fully formulated powder coating composition,then 7 microns is the pertinent D50 for the final polymer particles.

In embodiments in which one or more charge control agents are present onthe surface of the polymer particles, the above particle sizedistributions (e.g., D50, D90, D95, and D99, whether determined by laserdiffraction particle size analysis, DIA, or DMA), apply to the overallpolymer particles inclusive of the charge control agent(s) present onthe polymer particles.

Although the powder polymer powder particles, and optionally also theoverall coating composition (i.e., powder coating composition as awhole), preferably have a narrow or very narrow distribution of particlesizes in an effort to get a very smooth coating (e.g., as opposed to anorange-peel appearance), as well as to minimize the amount of appliedcoating material and thus cost, it is contemplated that powder coatingcompositions of the disclosure may include polymer particles havingparticle sizes outside the particle size parameters described above.Preferably, the total amount of such optional “larger” and/or “smaller”polymer particles or other particles included in the powder coatingcomposition is sufficiently low so that the desired properties of thepowder coating composition and/or hardened coating are substantiallypreserved (e.g., the desired application properties of the powdercoating composition; the desired adhesion, flexibility, chemicalresistance, coating aesthetics, etc., of the cured coating). In suchembodiments, preferably a substantial majority, by volume %, (e.g., 65%or more, 80% or more, 90% or more, 95% or more, 99% or more, etc.) ofthe total particles present in the powder coating composition exhibit aparticle size pursuant to the particle size parameters described above.

A useful method for determining particle sizes of the primary polymerparticles before agglomeration and other starting materials (e.g.,charge control agents, lubricants, etc.) is laser diffraction particlesize analysis. An exemplary device for such analysis is a BeckmanCoulter LS 230 Laser Diffraction Particle Size Analyzer or equivalent,calibrated as recommended by the manufacturer. It is believed that theparticle size analysis of this analyzer embodies the principles ofInternational Standard ISO 13320:2009(E).

Samples for laser diffraction particle size analysis can be prepared,for example, by diluting the samples in a substantially non-swellingsolvent (such as cyclohexanone or 2-butoxyethanol) and shaking themuntil evenly dispersed. The choice of a suitable solvent will dependupon the particular particles to be tested. Solvent screening tests mayneed to be conducted to identify a suitable substantially non-swellingsolvent. By way of example, a solvent in which a polymer particle swellsby about 1% or less (as determined by laser diffraction particle sizeanalysis) would be considered a substantially non-swelling solvent.

A useful method for determining particle sizes of the polymer powderparticles, which may or may not be agglomerated, or the powder coatingcompositions, is also laser diffraction particle size analysis ordynamic image analysis (DIA). DIA measures size (as well as otherparameters) based on particle images, according to, e.g., ISO 13322-2(2006) test method, using a CAMSIZER X2 device (Retsch Technology GmbH,Haan, Germany) equipped with the X-Jet plug-in cartridge and its relatedsoftware, according to device manufacturer's recommendations. Forsamples where a measurable portion of the powder coating particles maybe less than one micron in diameter, laser diffraction particle sizeanalysis (using, for example, the instrument listed above) is a suitablesubstitute for DIA.

The DIA method uses a flow of particles passing a camera system in frontof an illuminated background. A dynamic image analysis system measuresfree falling particles and suspensions, and also features dispersion byair pressure for those particles that are inclined to agglomerate. Awide range of size and shape parameters are measured using particleimages. Size parameters typically include length, width, and diameter ofan equivalent circle. The particle width is the common DIA parameterused to compare to sieve analysis.

Powder samples for dynamic image analysis can be prepared, for example,by dispersing a sample of the powder to be measured in an appropriatefluid. The prepared samples can then be measured in a dynamic imageanalyzer such as the CAMSIZER X2, which employs a dynamic imagingtechnique, rather than actual physical sieving of the particles. Samplesare dispersed by pressurized air and passed through a gap illuminated bytwo bright, pulsed LED light sources. The images of the dispersedparticles (more specifically of their shadows, or projections) are thenrecorded by two digital cameras and analyzed for size and shape in orderto determine a variety of length and width descriptors for theparticles, as required, e.g., by ISO test method 13322-2 (2006) (onparticle size analysis via dynamic imaging). Such descriptors include,e.g., the width of the particle (i.e., the shortest chord of themeasured set of maximum chords of a particle's projection (Camsizerparameter X_(c) min, also called the minimum largest chord diameter));the maximum Feret diameter (Camsizer parameter XFe max); or the aspectratio AR (Camsizer parameter b/h). The particle width is the preferredparticle size parameter since this parameter is most closely related tophysical screening using sieving techniques. A particle with a widthsmaller than a sieve aperture is able to pass the sieve even if thelength of such particle is larger than the width. Thus, the terms“particle size” and “sieve diameter” are nearly the same, and may beused interchangeably herein.

An alternative method for determining particle sizes of the polymerpowder particles, which may or may not be agglomerated, the primarypolymer particles before agglomeration and other starting materials(e.g., charge control agents, lubricants, etc.), or the powder coatingcompositions, uses differential mobility analysis (DMA). The particlecharge could be determined by using differential mobility analysis (DMA)to separate particles based on their ion mobility, followed by detectionusing an aerodynamic particle spectrometer (APS) or optical particlespectrometer (OPS) to determine particle size distribution. Details ofthis approach are included by reference (J. Phys. Chem. B, 2009, 113,970-976).

It will be understood by those skilled in the art that the particle sizeof the primary particles can be measured prior to the coating process,but this cannot be readily determined once agglomerates are formed. Thatis, the particle size of the primary particles that form agglomerates isdetermined based on the starting materials. Furthermore, to measure theparticle size of agglomerates, a sample of the agglomerates is collectedduring the coating process (e.g., during a spray drying process). Oncethe coating is formed, an accurate determination of the particle size ofthe agglomerates cannot be readily determined.

Powder polymer particles of the disclosure may be of any suitable shape,including, for example, flake, sheet, rod, globular, potato-shaped,spherical, or mixtures thereof. For example, precipitated polymerparticles are typically spherical. In certain embodiments, the particlesare potato-shaped or spherical, or a mixture thereof.

While any suitable powder polymer particles may be used, preferredpolymer particles are chemically produced polymer particles. Chemicallyproduced powders can be generically defined as fine powders prepared bymethods other than mechanical processing (e.g., other than bytraditional grinding). Such polymer particles have surface morphologiesand/or particle shapes that are distinct from those typically achievedvia mechanical processing means (e.g., grinding, milling, and the like).Such mechanical techniques entail taking larger size solid masses ofpolymer material and breaking them up in some manner to produce smallersize polymer particles. Such processes, however, typically yieldirregular, angular particle shapes and rough, irregular surfacemorphologies and result in wide particle size distributions, therebynecessitating additional filtering to achieve a desired particle sizedistribution, which results in waste and additional cost. The polymerparticles resulting from such mechanical processes are often referred toas “pulverized” or “ground” (conventionally prepared) particles. By wayof example, see FIG. 1A, which shows a scanning electron microscope(SEM) image of conventional milled polyester powder coating particlesthat are angular, irregular, and have a broad particle sizedistribution.

In contrast, chemically produced polymer particles tend to have moreregular and smooth surface morphologies and more regular and consistentparticle shapes and sizes. In addition, the particle size distributioncan be more exactly targeted and controlled, without generatingappreciable waste. While not intending to be bound by theory, it isbelieved the enhanced homogeneity and regularity of chemically producedparticles (e.g., in terms of shape, surface morphology, and particlesize distribution) relative to mechanically produced particles will leadto better and more predictable and efficient transfer and applicationonto substrate and ultimately better coating performance properties forhardened adherent packaging coatings produced therefrom. By way ofexample, see FIGS. 1B (generally potato shaped particles) and 1C(generally spherical particles), which show chemically produced polymerparticles having a generally narrow particle size distribution.

Examples of chemical processes for producing polymer particles includepolymerization, such as interfacial polymerization, polymerization inorganic solution, emulsion or dispersion polymerization in aqueousmedium; dispersion of polymers in surfactants (e.g., in disperse orcontinuous phases) using low molecular weight or polymeric hydrophilic,hydrophobic, or fluorophilic surfactants; precipitation of polymers,such as controlled precipitation; melt blending polymers; particleaggregation; microencapsulation; recrystallization; core-shellformation; as well as other processes that form “composite” powderpolymer particles.

In certain embodiments, the powder polymer particles (in certainembodiments, all the particles of the overall powder coatingcomposition) have a shape factor of at least 100, and in certainembodiments at least 120. In certain embodiments (e.g., using ground orpulverized particles), the shape factor may be up to 165, or up to 155,or up to 140. Accordingly, the particles may be spherical (having ashape factor of from 100 to less than 120) or potato shaped (having ashape factor of from at least 120 up to 140) or a mixture of sphericaland potato shaped. In contrast, conventional mechanically producedpolymer particles typically have a shape factor of greater than 145. Incertain embodiments, the powder polymer particles are preferably potatoshaped. The shape factor can be determined using the following equation:

Shape  Factor = ((ML)²/A) × (π/4)) × 100wherein: ML=Maximum Length of Particle (sphere=2r); and

-   -   A=Projected Area (sphere=πr²).

Shape factor can be determined, for example, using a flow-type particledynamic image analyzer (DIA) CAMSIZER X2. Particle shape parametersinclude convexity, sphericity, symmetry, and aspect ratio (ratio oflength to width). The sample can be prepared, for example, using thesample preparation described herein for particle size measurement.

Shape factor can also be determined by Scanning Electron Microscopy(SEM), using image analysis to determine an aspect ratio. For example, arepresentative powder sample could be transferred to a piece of carbonadhesive tape and then examined using a Vega3 Tescan SEM. An image couldthen be obtained using either a secondary electron detector or abackscattering electron detector, at an appropriate accelerating voltageand detection angle to achieve acceptable contrast between the particlesand the background. Imaging analysis could then be done on astatistically relevant number of particles to determine the averageaspect ratio using, for example, MountainLabs Expert (version 8.0)software.

It may also be possible to determine particle shape via the DMA methoddescribed above (J. Phys. Chem. B, 2009, 113, 970-976).

In certain embodiments, the powder polymer particles (in certainembodiments, all the particles of the overall powder coatingcomposition) have a compressibility index of at least 1, and in certainembodiments up to 20. In certain embodiments, the compressibility indexmay be 1 to 10, 11 to 15, or 16 to 20. The compressibility index can bedetermined using the following equation:

Compressibility  Index = ((Tap  Density − Bulk  Density)/(Tap  Density)) × 100wherein the tap density and the bulk are each determined pursuant toASTM D7481-18 (2018).

In certain embodiments, the powder polymer particles (in certainembodiments, all the particles of the overall powder coatingcomposition) have a Haussner Ratio of at least 1.00, and in certainembodiments up to 1.25. In certain embodiments, the Haussner Ratio is1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25. The Haussner Ratio can bedetermined using the following equation:

Haussner  Ratio = Tap  Density/Bulk  Densitywherein tap density and bulk density are as defined/determined above.

In certain embodiments, the powder polymer particles have at least fairflow characteristics (e.g., have a compressibility index of 16 to 20 anda Haussner Ratio is 1.19 to 1.25), or at least good flow characteristics(e.g., have a compressibility index of 11 to 15 and a Haussner Ratio is1.12 to 1.18), or excellent flow characteristics (e.g., have acompressibility index of 1 to 10 and a Haussner Ratio is 1.00 to 1.11).

Similar to the particle size distributions (e.g., D50 and the like)discussed above for the powder polymer particles, the shape factor,compressibility index, and Haussner Ratio, should be inclusive of anyadditional materials (e.g., charge control agent) that may optionally bepresent on the surface of the polymer particles in the final powdercoating composition.

In preferred embodiments, the overall powder coating compositionexhibits one or more of, two or more of, three or more of, four or moreof, five or more of, and preferably all of, a D50, a D90, a D95, a D99,a shape factor, a compressibility index, and a Haussner Ratio fallingwithin the ranges disclosed above for the powder polymer particles.

Although as discussed above, chemically produced powder polymerparticles are presently preferred, mechanically produced particles(e.g., via grinding, milling, and the like) may be used. If used, suchmechanically produced powder polymer particles should preferably (i) beused in minor amounts relative to the overall powder coating compositionor (ii) exhibit both a particle size distribution and a shape factor,and preferably also a Hausner ratio, pursuant to the ranges disclosedherein. With respect to (ii) above, it may not be possible to achievesuch powder polymer particle populations using currently availablemechanical processing techniques, at least not without incurringprohibitive processing costs.

In certain embodiments, the powder polymer particles are in the form ofagglomerates (i.e., assemblies of primary polymer particles). In certainembodiments, the agglomerates (i.e., clusters) may have a particle sizeof up to 25 microns, up to 20 microns, up to 15 microns, or up to 10microns. Although the lower size range of the agglomerate particle sizesis not restricted, typically the particle sizes will be at least 1micron, at least 2 microns, at least 3 microns, or at least 4 microns.In certain embodiments, the primary polymer particles have a primaryparticle size of at least 0.05 micron, and in certain embodiments, up to8 microns, up to 5 microns, up to 3 microns, up to 2 microns, or up to 1micron. The primary particle size may be determined by laser diffractionparticle size analysis, or DMA, of starting materials, and the particlesize of the polymer agglomerates (e.g., of the agglomerates collectedduring a spray drying process) may be determined by dynamic imageanalysis (DIA), laser diffraction particle size analysis, or DMA.

Agglomerated particles are typically formed by spray drying.Agglomerates are assemblies of primary particles, the latter of whichare formed by a polymerization process. The spray drying processtypically involves forming liquid droplets, wherein each dropletincludes primary particles therein, using a spray nozzle. The dropletsare then dried to form agglomerates (i.e., each of which is a cluster orassembly of the primary particles that were in each droplet). Theparticle size of an agglomerate, which may be referred to as thesecondary particle size, is determined by the number of primaryparticles within the agglomerate. This can be controlled by the size ofthe liquid droplet and/or the concentration of primary particles withineach droplet. For example, small agglomerates may be formed byincreasing the spray nozzle pressure to form a fine mist of smalldroplets. Also, small agglomerates may be formed by reducing theconcentration of the primary particles in the liquid, but using lowerspray nozzle pressure and forming larger droplets.

Each powder polymer particle may be formed from a single type of polymermaterial or may include two or more different types of polymermaterials. In addition to one or more types of polymer materials, ifdesired, the powder polymer particles, which may or may not beagglomerated, may incorporate up to 50 wt-% of one or more optionaladditives, based on the total weight of the powder polymer particles.Thus, preferably, the powder polymer particles include one or morepolymers in an amount of at least 50 wt-%, based on the total weight ofthe powder polymer particles. More preferably, the powder polymerparticles include one or more polymers in an amount of at least 60 wt-%,at least 70 wt-%, at least 80 wt-%, at least 90 wt-%, at least 95 wt-%,at least 98 wt-%, at least 99 wt-%, or 100 wt-%, based on the totalweight of the powder polymer particles.

Such optional additives may include, for example, lubricants, adhesionpromoters, crosslinkers, catalysts, colorants (e.g., pigments or dyes),ferromagnetic particles, degassing agents, levelling agents, wettingagents, surfactants, flow control agents, heat stabilizers,anti-corrosion agents, adhesion promoters, inorganic fillers, metaldriers, and combinations thereof. Such optional additives mayadditionally, or alternatively, be present in other particles that areincluded in the powder coating composition in addition to the powderpolymer particles.

The polymer particles may include any suitable combination of one ormore thermoplastic polymers, one or more thermoset polymers, or acombination thereof. In certain embodiments, the polymer particles mayinclude any suitable combination of one or more thermoplastic polymers.The term “thermoplastic” refers to a material that melts and changesshape when sufficiently heated and hardens when sufficiently cooled.Such materials are typically capable of undergoing repeated melting andhardening without exhibiting appreciable chemical change. In contrast, a“thermoset” refers to a material that is crosslinked and does not“melt.”

In certain embodiments, the polymer material has a melt flow indexgreater than 15 grams/10 minutes, greater than 50 grams/10 minutes, orgreater than 100 grams/10 minutes. In certain embodiments, the polymermaterial has a melt flow index of up to 200 grams/10 minutes, or up to150 grams/10 minutes. In some embodiments, the powder coatingcomposition as a whole exhibits such a melt flow index. The “melt flowindex” referred to herein is measured pursuant to ASTM D1238-13 (2013)at 190° C. and with a 2.16 kilogram weight.

In certain embodiments, the polymer particles are made fromsemi-crystalline, crystalline polymers, amorphous polymers, orcombinations thereof. Suitable semi-crystalline or crystalline polymersmay exhibit any suitable percent crystallinity. In some embodiments, thepowder coating composition of the disclosure includes at least onesemi-crystalline or crystalline polymer having a percent crystallinity(on a volume basis) of at least 5%, at least 10%, or at least 20%. Byway of example, the percent crystallinity for a given polymer may beassessed via differential scanning calorimetry (DSC) testing using thefollowing equation:

Percent  crystallinity  (%) = [A/B] × 100

-   wherein: “A” is the heat of fusion of the given polymer (i.e., the    total area “under” the melting portion of the DSC curve) in Joules    per gram (J/g); and “B” is the heat of fusion in J/g for the 100%    crystalline state of the polymer.

For many polymers, a theoretical B value may be available in thescientific literature and such value may be used. For polyesterpolymers, for example, if such a B value is not available in theliterature, then a B value of 145 kg may be used as an approximation,which is the heat of fusion for 100% crystalline polybutyleneterephthalate (PBT) as reported in: Cheng, Stephen; Pan, Robert; andWunderlich, Bernard; “Thermal analysis of poly(butylene terephthalate)for heat capacity, rigid-amorphous content, and transition behavior,”Macromolecular Chemistry and Physics, Volume 189, Issue 10 (1988):2443-2458.

In certain embodiments of the powder coating compositions of thedisclosure, at least one polymer material of the polymer particles (andmore preferably substantially all, or all, of the polymer materialpresent in the polymer particles) is at least semi-crystalline (e.g.,semi-crystalline or crystalline). In certain embodiments, the polymerparticles may include amorphous polymer material or a blend of at leastsemi-crystalline polymer material and amorphous polymer material.ASTM-D3418-15 (2015) is an example of a useful methodology for assessingthe crystallization properties (crystallization peak temperature) ofpolymers.

The polymers used may exhibit any suitable glass transition temperature(Tg) or combinations of Tg's. In certain embodiments, the powder polymerparticles are made from an amorphous polymer having a glass transitiontemperature (Tg) of at least 0° C., at least 30° C., at least 40° C., atleast 50° C., at least 60° C., or at least 70° C. and in certainembodiments, a Tg of up to 150° C., up to 125° C., up to 110° C., up to100° C., or up to 80° C.

Lower Tg polymers (e.g., having a Tg lower than 40° C., such as thosewith a Tg of at least 0° C. or at least 30° C.) may be used in makingthe powder polymer particles used herein at long as the particlesinclude at least one polymer with a higher Tg (e.g., at least 40° C.).

The polymer particles may additionally be of a core-shell morphology(i.e., the outer portion, or shell, of the polymer particle is of adifferent composition than the inner portion, or core). In such cases,the shell ideally comprises 10% by weight or greater of the totalpolymer particles, and the Tg preferences above would only apply to theshell of the polymer particle. In other words, the shell of the polymerparticle is preferably made from a polymer having a Tg of at least 40°C., at least 50° C., at least 60° C., or at least 70° C., and a Tg of upto 150° C., up to 125° C., up to 110° C., up to 100° C., or up to 80° C.

In certain embodiments, the powder polymer particles are made from acrystalline or semi-crystalline polymer having a melting point of atleast 40° C., and in certain embodiments, a melting point of up to 130°C.

In certain preferred embodiments, substantially all (i.e., more than 50wt-%) of the polymer material of the polymer particles exhibits such amelting point or Tg. Classic amorphous polymers do not, for example,exhibit any discernible melting point (e.g., do not exhibit a DSCmelting peak) nor include any crystalline regions. Thus, such classicamorphous polymers would be expected to exhibit a percent crystallinityof 0%. Accordingly, powder coating compositions of the disclosure mayinclude one or more amorphous polymers having a percent crystallinity of0% or substantially 0%. If desired, however, powder coating compositionsof the disclosure may include one or more “amorphous” polymers having apercent crystallinity other than 0 (e.g., less than 5%, less than 2%,less than 1%, less than 0.5%, less than 0.1%, etc.).

The one or more polymers of the polymer particles may be aliphatic oraromatic, or a combination of one or more aliphatic polymers and one ormore aromatic polymers. Similarly, the one or more polymer may besaturated or unsaturated, or a combination of one or more saturatedpolymers and one or more unsaturated polymers.

Suitable polymer particles can be prepared from water (e.g., latexpolymers) or from organic solvents (e.g., nonane, decane, dodecane, orisohexadecane), or combinations thereof. Water-based polymers arepreferred because of cost considerations, to keep VOC levels down duringprocessing, and to keep residual organic solvents out of the powdercoating compositions.

In certain embodiments, the powder polymer particles are emulsion,suspension, solution, or dispersion polymerized polymer particles (i.e.,particles made from an emulsion, suspension, solution, or dispersionpolymerization process). Typically, such polymers includeself-emulsifiable groups (e.g., carboxylic, sulphonic, phosphonic acidgroups, or salts thereof), although this is not a requirement.Neutralizing agents (e.g., amines, ammonia, or ammonium hydroxide),particularly volatile ones, can also be used in making such polymerparticles, as is well-known to those skilled in the art. Conversely, ifdesired, base groups that are neutralized with acids may also be used.Non-ionic polar groups may also alternatively or additional be used.

In certain embodiments, the powder polymer particles are precipitatedpolymer particles (i.e., particles made from a precipitation process).In certain embodiments, the powder polymer particles can be formed viapolymerization in liquid media followed by a suitable drying process(e.g., spray drying, vacuum drying, fluid bed drying, radiant drying,flash drying, and the like.) In certain embodiments, the powder polymerparticles can be formed via melt-blending (e.g., using a kneader, mixer,extruder, etc.) optionally coupled to a dispenser such as used foremulsification (see, e.g., U.S. Pat. No. 6,512,024 (Pate et al.) for adescription of such process equipment). In certain embodiments, however,the powder polymer particles are not ground polymer particles or polymerparticles formed from other similar fracturing or pulverizationprocesses. Preferably, the powder polymer particles are spray driedparticles.

In certain embodiments, the polymer of the powder polymer particles maybe a polyacrylic (i.e., acrylic, acrylate, or polyacrylate), polyether,polyolefin, polyester, polyurethane, polycarbonate, polystyrene, or acombination thereof (i.e., copolymer or mixture thereof such asacrylonitrile butadiene styrene). In certain embodiments, the polymersmay be engineering plastics. Engineering plastics are a group ofthermoplastic materials that have better mechanical and/or thermalproperties than the more widely used commodity plastics (such aspolystyrene, polypropylene, and polyethylene). Examples of engineeringplastics include acrylonitrile butadiene styrene (ABS), polycarbonates,and polyamides. Preferably, the polymer of the powder polymer particlesis a polyacrylic, a polyether, a polyolefin, a polyester, or acombination thereof.

Individual particles may be made of one polymer or two or more polymers.Individual particles may be uniform throughout or have a “core-shell”configuration having 1, 2, 3, or more “shell” layers or have a gradientarchitecture (e.g., a continuously varying architecture). Such“core-shell” particles may include, for example, multi-stage latexescreated via the emulsion polymerization of two or more different stages,emulsion polymerizations conducted using a polymeric surfactant, orcombinations thereof. Populations of particles may include mixtures ofpolymers, including mixtures of uniform and core-shell particles.

In certain embodiments, the inclusion of a sufficient number of cyclicgroups, and in some embodiments aryl and/or heteroaryl groups (e.g.,phenylene groups), in the polymers is an important factor for achievingsuitable coating performance for food-contact packaging coatings,especially when the product to be packaged is a so called “hard-to-hold”food or beverage product. Sauerkraut is an example of a hard-to-holdproduct. Although cyclic groups providing such performance are oftenaryl or heteroaryl groups, suitable aliphatic cyclic groups such as,e.g., aliphatic bridged bicyclic (e.g., norbornane or norbornenegroups), aliphatic bridged tricyclic groups (e.g., tricyclodecanegroups), or cyclobutane groups (e.g., as provided using structural unitsderived from 2,2,4,4-tetramethyl-1,3-cyclobutanediol), cyclobutenegroups, or spirodicyclic groups (e.g., as provided using3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane(PSG)) may provide such performance.

In certain embodiments such as, for example, when the polymer particlesare formed from certain polyether or polyester polymers, cyclic groups,and more preferably aryl and/or heteroaryl groups, preferably constituteat least 25 wt-%, more preferably at least 30 wt-%, even more preferablyat least 35 wt-%, and optimally at least 45 wt-% of such polymers. Theupper concentration of cyclic groups (e.g., aryl/heteroaryl groups) isnot particularly limited, but preferably the amount of such groups isconfigured such that the Tg of the polymer is preferably within the Tgranges discussed herein. The total amount of cyclic groups (e.g., aryland/or heteroaryl groups) in such polymers will typically constituteless than about 80 wt-%, more preferably less than 75 wt-%, even morepreferably less than about 70 wt-%, and optimally less than 60 wt-% ofthe polyether polymer. The total amount of cyclic groups (e.g., aryland/or heteroaryl groups) in such polymers can be determined based onthe weight of cyclic group-containing polymerizable compound (e.g.,aryl- or heteroaryl-containing polymerizable compound) incorporated intothe polymers and the weight fraction of such polymerizable compound thatconstitutes cyclic groups (e.g., aryl or heteroaryl groups).

Preferred aryl or heteroaryl groups include less than 20 carbon atoms,more preferably less than 11 carbon atoms, and even more preferably lessthan 8 carbon atoms. The aryl or heteroaryl groups preferably have atleast 4 carbon atoms, more preferably at least 5 carbon atoms, and evenmore preferably at least 6 carbon atoms. Substituted or unsubstitutedphenylene groups are preferred aryl or heteroaryl groups.

In some embodiments, at least some, or even all, of the cyclic groupsare polycyclic groups (e.g., bicyclic, tricyclic, or polycyclic groupshaving 4 or more rings).

In certain embodiments, the powder polymer particles may include apolyester polymer. Suitable polyesters include polyesters formed fromone or more suitable polycarboxylic acid components (e.g., dicarboxylicacid components, tricarboxylic acid components, tetracarboxylic acidcomponents, etc.) and one or more suitable polyol components (e.g., diolcomponents, triol components, polyols having four hydroxyl groups,etc.). One or more other comonomers may optionally be used, if desired.Dicarboxylic acid components and diol components are preferred incertain embodiments.

Suitable dicarboxylic acid components include, for example, aromaticdicarboxylic acids such as terephthalic acid, isophthalic acid, phthalicacid, naphthalenedicarboxylic acid (e.g., 2,6-napthalene dicarboxylicacid), and furandicarboxylic acid (e.g., 2,5-furandicarboxylic acid);aliphatic dicarboxylic acids such as adipic acid, cyclohexanedicarboxylic acid, sebacic acid and azelaic acid; unsaturated acids suchas maleic anhydride, itaconic acid, and fumaric acid; and mixturesthereof. Examples of other suitable polycarboxylic acids (or anhydrides)include benzene-pentacarboxylic acid; mellitic acid; 1,3,5,7napthalene-tetracarboxylic acid; 2,4,6 pyridine-tricarboxylic acid;pyromellitic acid; trimellitic acid; trimesic acid;3,5,3′,5′-biphenyltetracarboxylic acid;3,5,3′,5′-bipyridyltetracarboxylic acid;3,5,3′,5′-benzophenonetetracarboxylic acid;1,3,6,8-acridinetetracarboxylic acid; 1,2,4,5-benzenetetracarboxylicacid; nadic anhydride; trimellitic anhydride; pyromellitic anhydride,and mixtures thereof. Anhydrides or esters of the aforementioned acidsand mixtures of such acids, anhydrides or esters may also be used.

Suitable diol components include, for example, polymethylene glycolsrepresented by the formula HO—(CH₂)_(n)—OH (where n is about 2 to 10)such as ethylene glycol, propylene glycol, butanediol, hexanediol anddecamethylene glycol; branched glycols represented by the formulaHO—CH₂—C(R₂)—CH₂—OH (where R is an alkyl group having 1 to 4 carbonatoms) such as neopentyl glycol; diethylene glycol and triethyleneglycol; diols having a cyclohexane ring such as cyclohexane dimethanol(CHDM); 2-methyl-1,3 propane diol; diols having a cyclobutane ring suchas 2,2,4,4-tetramethyl-1,3-cyclobutanediol; isosorbide;tricyclodecanedimethanol; spirodicyclic diols (e.g.,3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane(PSG)); and mixtures thereof. Glycerol, trimethylol propane (TMP), andother suitable trifunctional or higher polyols may also be used alone orin combination with any other suitable polyol.

In certain embodiments, the polyester polymer particles are made fromsemi-crystalline or crystalline polymers. Suitable exemplary crystallineand semi-crystalline polyester polymers include polyethyleneterephthalate (“PET”), copolymers of PET such as PET/I, polybutyleneterephthalate (“PBT”), polyethylene naphthalate (“PEN”),poly-1,4-cyclohexylenedimethylene terephthalate, and copolymers andcombinations thereof. In some embodiments, the polyester material may beformed from ingredients including dimer fatty acids. Non-limitingexamples of useful commercially available polyester materials mayinclude polyesters commercially available under the tradename DYNAPOLsuch as, for example, DYNAPOL L912 (includes polycyclic groups derivedfrom tricyclodecanedimethanol), DYNAPOL L952, DYNAPOL P1500, DYNAPOLP1500 HV (has a melting point temperature of about 170° C., a glasstransition temperature of about 20° C., and a number average molecularweight of approximately 20,000), DYNAPOL P1510, and DYNAPOL P1550 (eachavailable from Hiils AG and based on monomers including terephthalicacid and/or isophthalic acid); polyester materials commerciallyavailable under the TRITAN tradename (available from Eastman ChemicalCompany and based on monomers including2,2,4,4-Tetramethyl-1,3-cyclobutanediol); and polyester materialscommercially available under the tradename GRILTEX such as, for example,GRILTEX DD2267EG and GRILTEX D2310EG (each available from EMS-Chemie andbased on monomers including terephthalic acid and/or isophthalic acid).

Exemplary polyester polymers that may be used in making suitable powderpolymer particles are described, for example, in U.S. Pat. Pub. No.2014/0319133 (Castelberg et al.), U.S. Pat. Pub. No. 2015/0344732(Witt-Sanson et. al.), U.S. Pat. Pub. No. 2016/0160075 (Seneker et al.),International Application No. PCT/US2018/051726 (Matthieu et al.), U.S.Pat. No. 5,464,884 (Nield et al.), U.S. Pat. No. 6,893,678 (Hirose etal.), U.S. Pat. No. 7,198,849 (Stapperfenne et al.), U.S. Pat. No.7,803,415 (Kiefer-Liptak et al.), U.S. Pat. No. 7,981,515 (Ambrose etal.), U.S. Pat. No. 8,133,557 (Parekh et al.), U.S. Pat. No. 8,367,171(Stenson et al.), U.S. Pat. No. 8,574,672 (Doreau et al.), U.S. Pat. No.9,096,772 (Lespinasse et al.), U.S. Pat. No. 9,011,999 (Cavallin etal.), U.S. Pat. No. 9,115,241 (Gao et al.), U.S. Pat. No. 9,187,213(Prouvost et al.), U.S. Pat. No. 9,321,935 (Seneker et al.), U.S. Pat.No. 9,650,176 (Cavallin et al.), U.S. Pat. No. 9,695,264 (Lock et al.),U.S. Pat. No. 9,708,504 (Singer et al.), U.S. Pat. No. 9,920,217(Skillman et al.), U.S. Pat. No. 10,131,796 (Martinoni et al.), and U.S.Pat. Pub. No. 2020/0207516 (Seneker et al.).

In some embodiments, polyester polymers having C4 rings can be used suchas, for example, are present in certain structural segments derived fromcyclobutanediol-type compounds such as, e.g., including2,2,4,4-tetramethyl-1,3-cyclobutanediol). Exemplary such polyestersincluding such C₄ rings are described, for example, in WO2014/078618(Knotts et al.), U.S. Pat. No. 8,163,850 (Marsh et. al.), U.S. Pat. No.9,650,539 (Kuo et. al.), U.S. Pat. No. 9,598,602 (Kuo et. al.), U.S.Pat. No. 9,487,619 (Kuo et. al.), U.S. Pat. No. 9,828,522 (Argyropouloset al.), and U.S. Pat. Pub. No. 2020/0207516 (Seneker et al.).

In certain embodiments, the powder polymer particles may include apolyether polymer. In some embodiments, the polyether polymer contains aplurality of aromatic segment, more typically aromatic ether segments.The polyether polymer may be formed using any suitable reactants and anysuitable polymerization process. The polyether polymer may be formed,for example, from reactants including an extender compound (e.g., adiol, which is preferably a polyhydric phenol, more preferably adihydric phenol; a diacid; or a compound having both a phenol hydroxylgroup and a carboxylic group) and a polyepoxide. In certain preferredembodiments, the polyepoxide is a polyepoxide of a polyhydric phenol(more typically a diepoxide of, e.g. a diglycidyl ether of, a dihydricphenol). In some embodiments, (i) the polyhydric phenol compound is anortho-substituted diphenol (e.g., tetramethyl bisphenol F), (ii) thediepoxide is a diepoxide of an ortho-substituted diphenol (e.g.,tetramethyl bisphenol F), or (iii) both (i) and (ii).

In some embodiments, a polyether polymer is formed from reactantsincluding a diepoxide of an ortho-substituted diphenol (e.g., thediglycidyl ether of tetramethyl bisphenol F) and a dihydric phenolhaving only one phenol ring (e.g., hydroquinone, resorcinol, catechol,or a substituted variant thereof).

In certain embodiments, a polyether polymer is prepared from reactantsincluding a diepoxide (typically a diglycidyl ether or diglycidyl ester)that is not derived from a polyhydric phenol, and which includes one ormore backbone or pendant aryl or heteroaryl groups. Such aromaticdiepoxides may be prepared, for example, from aromatic compounds havingtwo or more reactive groups such as diols, diacids, diamines, and thelike. Suitable such exemplary aromatic compounds for use in forming thearomatic diepoxides include 1-phenyl-1,2-propanediol;2-phenyl-1,2-propanediol; 1-phenyl-1,3-propanediol;2-phenyl-1,3-propanediol; 1-phenyl-1,2-ethanediol; vanillyl alcohol;1,2-, 1,3- or 1,4-benzenedimethanol; furandimethanol (e.g.,2,5-furandimethanol); terephthalic acid; isophthalic acid; and the like.

In some embodiments, a polyether polymer is prepared from reactantsincluding one or more aliphatic polyepoxides, which are typicallyaliphatic diepoxides, and more typically cycloaliphatic diepoxides.Exemplary aliphatic diepoxides include diepoxides of (which aretypically diglycidyl ethers of): cyclobutane diol (e.g.,2,2,4,4-tetramethyl-1,3-cyclobutanediol), isosorbide,cyclohexanedimethanol, neopentyl glycol, 2-methyl 1,3-propanediol,tricyclodecanedimethanol,3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane(PSG), and mixtures thereof.

Exemplary reactants, polymerization processes, and polyether polymersthat can be used in making suitable powder particles are described inU.S. Pat. No. 7,910,170 (Evans et al.), U.S. Pat. No. 9,409,219(Niederst et al.), U.S. Pat. Pub. No. 2013/0280455 (Evans et al.), U.S.Pat. Pub. No. 2013/0316109 (Niederst et al.), U.S. Pat. Pub. No.2013/0206756 (Niederst et al.), U.S. Pat. Pub. No. 2015/0021323(Niederst et al.), International Pub. Nos. WO 2015/160788 (ValsparSourcing), WO 2015/164703 (Valspar Sourcing), WO 2015/057932 (ValsparSourcing), WO 2015/179064 (Valspar Sourcing), and WO 2018/125895(Valspar Sourcing).

In some embodiments, the polyether polymers are not formed usingingredients that include any bisphenols or any epoxides of bisphenols,although non-intentional, trace amounts may potentially be present dueto, e.g., environmental contamination. Examples of suitable reactantsfor forming such bisphenol-free polyether polymers include any of thediepoxides derived from materials other than bisphenols described in thepatent documents referenced in the preceding paragraph and any of theextender compounds other than bisphenols disclosed in such patentdocuments. Hydroquinone, catechol, resorcinol, and substituted variantsthereof, are non-limiting examples of suitable extender compounds foruse in making such bisphenol-free polyether polymers.

In certain embodiments, the powder polymer particles may include apolymer formed via free-radical polymerization of ethylenicallyunsaturated monomers, with acrylic polymers being preferred examples ofsuch polymers. Such polymers are referred to herein as “acrylicpolymers” for convenience given that such polymers typically include oneor more monomers selected from (meth)acrylates or (meth)acrylic acid.Preferred acrylic polymers include organic-solution polymerized acrylicpolymers and emulsion polymerized acrylic latex polymers. A suitableacrylic polymer includes a reaction product of components that include a(meth)acrylic acid ester, an optional ethylenically unsaturated mono- ormulti-functional acid, and an optional vinyl compound. For example, theacrylate film-forming polymer could be a reaction product of componentsthat include ethyl acrylate, acrylic acid, and styrene (preferably inthe presence of 2,2′-azobis(2-methyl-butyronitrile) and tert-butylperoxybenzoate free radical initiators). In some embodiments, onlyacrylic polymers that are free from structural units derived fromstyrene are used.

Examples of suitable (meth)acrylic acid esters (i.e., methacrylic acidesters and acrylic acid esters) include methyl (meth)acrylate, ethyl(meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl(meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, isoamyl(meth)acrylate, hexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate,2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, decyl(meth)acrylate, isodecyl (meth)acrylate, benzyl (meth)acrylate,2-hydroxypropyl (meth)acrylate, lauryl (meth)acrylate, isobornyl(meth)acrylate, octyl (meth)acrylate, and nonyl (meth)acrylate. Anysuitable isomer or combination of isomers of the above may be used. Byway of example, disclosure of “butyl (meth)acrylate” is intended todisclose all isomers such as n-butyl (meth)acrylate, sec-butyl(meth)acrylate, tert-butyl (meth)acrylate, and the like. In general, asdisclosed herein, unless specifically indicated to the contrary,disclosure of all isomers for a given monomer is intended.

Examples of suitable ethylenically unsaturated mono- or multi-functionalacids include methacrylic acid, acrylic acid, crotonic acid, itaconicacid, maleic acid, mesaconic acid, citraconic acid, sorbic acid, andfumaric acid.

Examples of suitable vinyl compounds include styrene, halostyrene,isoprene, a conjugated butadiene, alpha-methylstyrene, vinyl toluene,vinyl naphthalene, vinyl chloride, acrylonitrile, methacrylonitrile,vinyl acetate, vinyl propionate, vinyl cyclohexane, vinyl cyclooctane,vinyl cyclohexene, and vinyl stearate. As previously discussed, in someembodiments, styrene is not used.

Examples of commercially available acrylic polymers include thoseavailable under the trade names VIACRYL SC 454/50BSNB, VIACRYLSC383w/50WA, and VANCRYL 2900 DEV (all from Cytec Industries Inc., WestPatterson, NJ), as well as NEOCRYL A-639, NEOCRYL XK-64, URACON CR203M3, and URACON CS113 S1G (all from DSM Neoresins BV, 5140 AC Waalwijk,Netherlands).

Exemplary acrylic polymers that may be used in making suitable powderparticles are described in U.S. Pat. No. 8,168,276 (Cleaver et al.),U.S. Pat. No. 7,189,787 (O'Brien), U.S. Pat. No. 7,592,047 (O'Brien etal.), U.S. Pat. No. 9,181,448 (Li et al.), U.S. Pat. No. 9,394,456(Rademacher et al.), U.S. Pat. Pub. No 2016/0009941 (Rademacher et al.),U.S. Pat. Pub. No. US2016/0376446 (Gibanel et al.), U.S. Pat. Pub. No.2017/0002227 (Gibanel et al.), U.S. Pat. Pub. No. 2018/0265729 (Gibanelet al.), WO2016/196174 (Singer et al.), WO2016/196190 (Singer et al.),WO2017/112837 (Gibanel et al.), WO2017/180895 (O'Brien et. al.),WO2018/085052 (Gibanel et al.), WO2018/075762 (Gibanel et al.),WO2019/078925 (Gibanel et al.), WO2019/046700 (O'Brien et al.), andWO2019/046750 (O'Brien et al.).

In certain embodiments, the powder polymer particles include dried latexparticles that include both polyether polymer and acrylic polymer.Examples of such latex particles are described, e.g., in WO2017/180895(O'Brien et. al.) and International App. No. WO2019046700 (O'Brien etal.).

In certain embodiments, the powder polymer particles may include apolyolefin polymer. Examples of suitable polyolefin polymers includemaleic-modified polyethylene, maleic-modified polypropylene, ethyleneacrylic acid copolymers, ethylene methacrylic acid copolymers, propyleneacrylic acid copolymers, propylene methacrylic acid copolymers, andethylene vinyl alcohol copolymers.

Examples of commercially available polyolefin polymers include thoseavailable under the trade names DOW PRIMACOR 5980i, DUPONT NUCREL,POLYBOND 1103, NIPPON SOARNOL (EVOH), ARKEMA OREVAC 18751, and ARKEMAOREVAC 18360. Exemplary polyolefin polymers that may be used in makingsuitable powder particles are described in U.S. Pat. No. 9,000,074(Choudhery), U.S. Pat. No. 8,791,204 (Choudhery), International Pub. No.WO 2014/140057 (Akzo Nobel), U.S. Pat. No. 8,722,787 (Romick et al.),U.S. Pat. No. 8,779,053 (Lundgard et al.), and U.S. Pat. No. 8,946,329(Wilbur et al.).

In some embodiments, suitable polyolefin particles are prepared fromaqueous dispersions of polyolefin polymer. See, for example, U.S. Pat.No. 8,193,275 (Moncla et al.) for a description of suitable processesfor producing such aqueous polyolefin dispersions. Examples ofcommercially available aqueous polyolefin dispersions include theCANVERA line of products available from Dow, including, for example, theCANVERA 1110 product, the CANVERA 3110-series, and the CANVERA3140-series. Dry powder polymer particles of the specificationsdisclosed herein can be achieved using any suitable process, includingany of the suitable processes disclosed herein such as, for example,spray drying. Preferably, spray drying is used to form dry powderpolymer particles of the specifications disclosed herein.

In some embodiments, the powder polymer particles may include anunsaturated polymer in combination with one or both of an ethercomponent or a metal drier. In some embodiments, the ether component ispresent in the unsaturated polymer itself. While not intending to bebound by theory, it is believed that the presence of a suitable amountof unsaturation (e.g., aliphatic or cycloaliphatic carbon-carbon doublebonds such as present in, e.g., norbornene groups and saturatedstructural units derived from maleic anhydride, itaconic acid,functionalized polybutadiene, and the like) in combination with asuitable amount of ether component or metal drier (e.g., aluminum,cobalt, copper, oxides thereof, salts thereof) can result in molecularweight build during thermal cure of the powder coating composition toform a hardened coating. See, for example, U.S. Pat. No. 9,206,332(Cavallin et al.) for further discussion of such reaction mechanisms andsuitable materials and concentrations. In some embodiments, the polymerof the powder polymer particles may have an iodine value of at least 10,at least 20, at least 35, or at least 50. The upper range of suitableiodine values is not particularly limited, but in most such embodimentsthe iodine value typically will not exceed about 100 or about 120. Theaforementioned iodine values are expressed in terms of the centigrams ofiodine per gram of the material. Iodine values may be determined, forexample, using ASTM D 5768-02 (Reapproved 2006) entitled “Standard TestMethod for Determination of Iodine Values of Tall Oil Fatty Acids.”

Optional Charge Control Agents

In certain embodiments of the powder coating compositions of the presentdisclosure, one or more charge control agents are included in thecoating composition. That is, in certain embodiments, the powder polymerparticles are in contact with one or more charge control agents.

In certain embodiments, one or more charge control agents are disposedon a surface of the powder polymer particles. In certain embodiments,the polymer particles are at least substantially coated, or evencompletely coated, with one or more charge control agents. In certainembodiments, one or more charge control agents are adhered to a surfaceof the powder polymer particles.

Charge control agent(s) enables the powder coating particles toefficiently accept a charge (preferably, a triboelectric charge) tobetter facilitate electrostatic application to a substrate. The chargecontrol agent(s) also allow the powder coating particles to bettermaintain a latent triboelectric charge for a longer period of time,avoiding a degradation of the electrostatic application properties overtime. In addition to the benefits achieved by incorporating one or morecharge control agents, the agent(s) should not negatively impact thesystem. For example, the charge control agent(s) should not interfere inany deleterious way with the function of the any component of theapplication equipment (such as the fuser) or the performance of thehardened coating (such as adhesion, color development, clarity, orproduct resistance).

Accordingly, such combination of particles and charge control agent(s)is referred to herein as “triboelectrically chargeable powder polymerparticles” (or simply “chargeable polymer particles” or “chargeableparticles”). The use and orientation of the charge control agent(s) withrespect to the powder polymer particles is well-known to those in thetoner printing industry.

In certain embodiments, during application to a substrate, the chargecontrol agent provides a charge to the powder polymer particles byfriction thereby forming charged (i.e., triboelectrically charged)powder polymer particles.

In certain embodiments, the charge control agents are for use withpositive charged powder coating compositions. In other embodiments, thecharge control agents are for use with negative charged powder coatingcompositions.

In certain embodiments, the charge control agent includes inorganicparticles, organic particles, or both (e.g., inorganic modified organicparticles or organometallic particles). In certain embodiments, thecharge control agent includes inorganic particles. Charge control agentscan be either positively charged or negatively charged.

In certain embodiments, the charge control agent particles may be of anysuitable size. Typically, the charge control agent particles haveparticle sizes in the sub-micron range (e.g., less than 1 micron, 100nanometers or less, 50 nanometers or less, or 20 nanometers or less),although any suitable size may be employed. In certain embodiments, theparticle size of the charge control agent particles is of 0.001 micronto 0.10 micron. A useful method for determining particle sizes of thecharge control agent particles is laser diffraction particle sizeanalysis, as described herein for the powder polymer particles.

Examples of suitable charge control agents include hydrophilic fumedaluminum oxide particles, hydrophilic precipitated sodium aluminumsilicate particles, metal carboxylate and sulfonate particles,quaternary ammonium salts (e.g., quaternary ammonium sulfate orsulfonate particles), polymers containing pendant quaternary ammoniumsalts, ferromagnetic particles, transition metal particles, nitrosine orazine dyes, copper phthalocyanine pigments, metal complexes of chromium,zinc, aluminum, zirconium, calcium, or combinations thereof.

Optional Additives

In certain embodiments, the powder coating composition of the presentdisclosure may include one or more other optional additives to providedesired effects. For example, such optional additives may be included inthe coating composition to enhance composition aesthetics, to facilitatemanufacturing, processing, handling, and application of the composition,and to further improve a particular functional property of the coatingcomposition or a hardened coating resulting therefrom. One or moreoptional additives may form a part of the particles themselves, such aspart of spray dried particles.

Because hardened coatings of the present disclosure are preferably usedon food-contact surfaces, it is desirable to avoid the use of additivesthat are unsuitable for such surfaces due to factors such as taste,toxicity, or other government regulatory requirements.

Examples of such optional additives, particularly those suitable for usein coatings used on food-contact surfaces, include lubricants, adhesionpromoters, crosslinkers, catalysts, colorants (e.g., pigments or dyes),ferromagnetic particles, degassing agents, levelling agents, wettingagents, surfactants, flow control agents, heat stabilizers,anti-corrosion agents, adhesion promoters, inorganic fillers, metaldriers, and combinations thereof. In certain embodiments, the powdercoating composition includes one or more lubricants, pigments,crosslinkers, or a combination thereof.

In certain preferred embodiments, powder coating compositions of thepresent disclosure include one or more lubricants, e.g., forflexibility. Examples of suitable lubricants include carnauba wax,synthetic wax (e.g., Fischer-Tropsch wax), polytetrafluoroethylene(PTFE) wax, polyolefin wax (e.g., polyethylene (PE) wax, polypropylene(PP) wax, and high-density polyethylene (HDPE) wax), amide wax (e.g.,micronized ethylene-bis-stearamide (EBS) wax), combinations thereof, andmodified version thereof (e.g., amide-modified PE wax, PTFE-modified PEwax, and the like). In some embodiments, the lubricants are micronizedwaxes, which may optionally be spherical. Lubricants facilitatemanufacture of metal cans, particularly metal riveted can ends and pulltabs, by imparting lubricity, and thereby flexibility, to sheets ofcoated metal substrates.

In certain embodiments, one or more lubricants may be present in apowder coating composition of the present disclosure in an amount of atleast 0.1 wt-%, at least 0.5 wt-%, or at least 1 wt-%, based on thetotal weight of the powder coating composition. In certain embodiments,one or more lubricants may be present in an amount of up to 4 wt-%, upto 3 wt-%, or up to 2 wt-%, based on the total weight of the powdercoating composition.

The lubricant may be present in the powder polymer particles, on thepowder polymer particles, in another ingredient used to form the powdercoating composition, or a combination thereof. The lubricant may also beapplied in a second powder coating composition that is applied in aseparate powder layer. For example, the lubricant may be applied in a“dust-on-dust” approach on a base powder layer including the powderpolymer particles of the present disclosure, prior to cure of the basepowder layer.

Examples of suitable commercially available lubricants include theCERETAN line of products from Munzig (e.g., the CERETAN MA 7020, MF5010, MM 8015, MXF 2999, MT 9120, MXD 3920, and the MXF 9899 products);the LUBA-PRINT line of products from Munzig (e.g., the LUBA-PRINT 255/B,276/A (ND), 351/G, 501/S-100, 749/PM, and CA30 products); the SST-52,S-483, FLUOROSLIP 893-A, TEXTURE 5347W, and SPP-10 products fromShamrock; the CERAFLOUR line of products from BYK (e.g., the CERAFLOUR981, 988, 996, 258, 970, and 916 products); and the CERACOL 607 productfrom BYK.

Particles sizes of some of these lubricants, and methods used todetermine such particle sizes as identified by the suppliers (although,herein, such lubricant particle sizes may be measured by laserdiffraction particle size analysis), are presented in the followingtable.

Supplier Lubricant Chemistry of Lubricant* Particle Size* Method*Munzing Ceretan MA 7020 Micronized ethylene- D99 < 20 μm/ LV 5 ISO 13320bis-stearamide wax D50 < 5 μm Munzing Ceretan MF 5010 Spherical,micronized PTFE D99 < 10 μm/ LV 5 ISO 13320 modified polyolefin wax D50< 4 μm Munzing Ceretan MM 8015 Sperical, micronized D99 < 15 μm/ LV 5ISO 13320 montan wax D50 < 6 μm Munzing Ceretan MXF 2999 Micronizedfunctional blend, D50 < 50 μm LV 5 ISO 13320 coated with PTFE MunzingCeretan MT 9120 High melting, spherical, D99 < 20 μm/ LV 5 ISO 13320micronized Fischer-Tropsch wax D50 < 7 μm Munzing Ceretan MXD 3920Coated, micronized wax with D99 < 20 μm/ LV 5 ISO 13320 diamond-likehardness D50 < 4 μm Munzing Ceretan MXF 9899 Spherical, micronizedfunctional D50 < 50 μm LV 5 ISO 13320 blend with PTFE coating MunzingLUBA-print 255/B Carnauba wax dispersion D50: 2-3 μm/ Picture-Particle-D98: <6 μm Analyzing System Munzing LUBA-print 276/APolyethylene-wax/PTFE dispersion D50: 2-3 μm/ Picture-Particle- D98: <8μm Analyzing System Munzing LUBA-print 351/G Functional blend waxdispersion D50: 2-3 μm/ Picture-Particle- D98: <5 μm Analyzing SystemMunzing LUBA-print 501/S-100 Polyethylene-wax dispersion D50: 2.5-4 μm/Picture-Particle- D98: <8 μm Analyzing System Munzing LUBA-print 749/PMAmide-wax dispersion D50: 2-3 μm/ Picture-Particle- D98: <5 μm AnalyzingSystem Munzing LUBA-print CA 30 Carnauba wax dispersion D98: 3.0 μmSingle pass test BYK Ceraflour 981 Micronized PTFE D50: 3 μm/ Laserdiffraction - D90: 6 μm volume distribution BYK Ceraflour 988Micronized, amide-modified D50: 6 μm/ Laser diffraction - polyethylenewax D90: 13 μm volume distribution BYK Ceraflour 996 Micronized,PTFE-modified D50: 6 μm/ Laser diffraction - polyethylene wax D90: 11 μmvolume distribution BYK Ceraflour 970 Micronized polypropylene wax D50:9 μm/ Laser diffraction - D90: 14 μm volume distribution BYK Ceraflour916 Micronized, medified HDPE D50: 46 μm/ Laser diffraction -wax/polymer mix D90: 82 μm volume distribution BYK Ceramat 258Dispersion of an oxidized 30 μm Hegman HDPE wax BYK Ceracol 607PTFE-modified polyethylene D50: 4 μm/ Laser diffraction - wax dispersionD90: 10 μm volume distribution *According to Manufacturer's Literature

In certain preferred embodiments, powder coating compositions of thepresent disclosure include one or more crosslinkers and/or catalysts.Additionally, or alternatively, the powder coating composition mayinclude one or more self-crosslinkable polymers. Examples of suitablecrosslinkers (e.g., phenolic crosslinker, amino crosslinker, or acombination thereof) and catalysts (e.g., a titanium-containingcatalyst, a zirconium-containing catalyst, or a combination thereof) aredescribed in U.S. Pat. No. 8,168,276 (Cleaver et al.).

The term “crosslinker” refers to a molecule capable of forming acovalent linkage between polymers or between two different regions ofthe same polymer. Examples of suitable crosslinkers includecarboxyl-reactive curing resins, with beta-hydroxyalkyl-amidecrosslinkers being preferred such crosslinkers (e.g., availablecommercially under the trade name PRIMID from EMS-Griltech (e.g. thePRIMID XL-552 and PRIMID QM-1260 products) and hydroxyl-curing resinssuch as, for example, phenolic crosslinkers, blocked isocyanatecrosslinkers, and aminoplast crosslinkers. Other suitable curing agentsmay include benzoxazine curing agents such as, for example,benzoxazine-based phenolic resins or hydroxy alkyl ureas. Examples ofbenzoxazine-based curing agents are provided in U.S. Pat. Pub. No.2016/0297994 (Kuo et al.). Examples of hydroxy alkyl ureas are providedin U.S. Pat. Pub. No. 2017/0204289 (Kurtz et al.).

Phenolic crosslinkers include the condensation products of aldehydeswith phenols. Formaldehyde and acetaldehyde are preferred aldehydes.Various phenols can be employed such as phenol, cresol, p-phenylphenol,p-tert-butylphenol, p-tert-amylphenol, and cyclopentylphenol.

Aminoplast crosslinkers are typically the condensation products ofaldehydes such as formaldehyde, acetaldehyde, crotonaldehyde, andbenzaldehyde with amino or amido group-containing substances such asurea, melamine, and benzoguanamine. Examples of suitable aminoplastcrosslinking resins include benzoguanamine-formaldehyde resins,melamine-formaldehyde resins, esterified melamine-formaldehyde, andurea-formaldehyde resins. One specific example of a suitable aminoplastcrosslinker is the fully alkylated melamine-formaldehyde resincommercially available from Cytec Industries, Inc. under the trade nameof CYMEL 303.

In some embodiments, the powder coating composition does not include anyadded crosslinkers. In such embodiment, the polymer of the powderparticles may, or may not, be a self-crosslinking polymer, depending onthe chemistry of the selected polymer and the desired coatingproperties.

In certain embodiments, one or more crosslinkers may be present in apowder coating composition of the present disclosure in an amount of atleast 0.1 wt-%, at least 1 wt-%, at least 2 wt-%, at least 5 wt-%, or atleast 8 wt-% based on the total weight of the powder coatingcomposition. In certain embodiments, one or more crosslinkers may bepresent in an amount of up to 40 wt-%, up to 30 wt-%, up to 20 wt-%, orup to 10 wt-%, based on the total weight of the powder coatingcomposition.

In certain preferred embodiments, powder coating compositions of thepresent disclosure include one or more colorants, such as a pigmentand/or dye. Examples of suitable colorants for use in the powder coatingcomposition include titanium dioxide, barium sulfate, carbon black, andiron oxide, and may also include organic dyes and pigments.

In certain embodiments, one or more colorants may be present in a powdercoating composition of the present disclosure in an amount of, forexample, at least 1 wt-%, at least 2 wt-%, at least 5 wt-%, at least 10wt-%, or at least 15 wt-%, based on the total weight of the powdercoating composition. In certain embodiments, one or more colorants maybe present in an amount of up to 50 wt-%, up to 40 wt-%, up to 30 wt-%,or up to about 20%, based on the total weight of the powder coatingcomposition. The use of a higher colorant concentration may beadvantageous to achieve good coverage with thinner coatings.

In certain embodiments, powder coating compositions of the presentdisclosure include one or more inorganic fillers. Exemplary inorganicfillers used in the powder coating composition of the present disclosureinclude, for example, clay, mica, aluminum silicate, fumed silica,magnesium oxide, zinc oxide, barium oxide, calcium sulfate, calciumoxide, aluminum oxide, magnesium aluminum oxide, zinc aluminum oxide,magnesium titanium oxide, iron titanium oxide, calcium titanium oxide,and mixtures thereof.

The inorganic fillers are preferably nonreactive, and may beincorporated into the powder coating composition in the form of apowder, preferably with a particle size distribution that is the same orsmaller than that of the blend of one or more powder polymer particles.

In certain embodiments, one or more inorganic fillers may be present ina powder coating composition of the present disclosure in an amount ofat least 0.1 wt-%, at least 1 wt-%, or at least 2 wt-%, based on thetotal weight of the powder coating composition. In certain embodiments,one or more inorganic fillers may be present in an amount of up to 20wt-%, up to 15 wt-%, or up to 10 wt-%, based on the total weight of thepowder coating composition.

In certain preferred embodiments, powder coating compositions of thepresent disclosure include one or more flow control agents. The flowcontrol agent may assist in achieving a uniform thin film and mayfurther assist in reducing lumping and dust issues that may otherwiseoccur with fine powder particles.

Examples of flow control agents are inorganic particles, such as silicaparticles (e.g., hydrophobic fumed silica particles, hydrophilic fumedsilica particles, hydrophobic precipitated silica particles, hydrophilicprecipitated silica particles), and organic resins, such aspolyacrylics.

Examples of commercially available materials for use as flow controlagents include the AEROSIL, AEROXIDE, and SIPERNAT lines of productsfrom Evonik (e.g., the AEROSIL R972, R816, 200, and 380 products; theAEROXIDE Alu C product; and the SIPERNAT D 17, 820A, 22 S, 50 S, and 340products); the BONTRON series of products from Orient Corporation ofAmerica (e.g., the BONTRON E-Series, S-Series, N-Series, and P-Serieslines of products); and the HDK line of pyrogenic silica products fromWacker (e.g., the HDK H1303VP, H2000/4, H2000T, and H3004 products).

An exemplary flow control agent for use in the powder coatingcomposition is a polyacrylate commercially available under the tradenamePERENOL from Henkel Corporation, Rocky Hill, CT Additionally usefulpolyacrylate flow control agents are commercially available under thetradename ACRYLON MFP from Protex France, and those commerciallyavailable from BYK-Chemie GmbH, Germany. Numerous other compounds knownto persons skilled in the art also may be used as a flow control agent.

In certain embodiments, one or more flow control agents may be presentin a powder coating composition of the present disclosure in an amountof at least 0.1 wt-%, or at least 0.2 wt-%, based on the total weight ofthe powder coating composition. In certain embodiments, one or more flowcontrol agents may be present in an amount of up to 5 wt-%, or up to 1wt-%, based on the total weight of the powder coating composition.

In certain preferred embodiments, powder coating compositions of thepresent disclosure include one or more surfactants. Examples of suitablesurfactants for use in the powder coating composition include wettingagents, emulsifying agents, suspending agents, dispersing agents, andcombinations thereof. In some embodiments one or more of the surfactantsmay be polymeric surfactant (e.g., an alkali-soluble resin). Examples ofsuitable surfactants for use in the coating composition includenon-ionic and anionic surfactants.

In certain embodiments, one or more surfactants may be present in apowder coating composition of the present disclosure in an amount of atleast 0.1 wt-%, or at least 0.2 wt-%, based on the total weight of thepowder coating composition. In certain embodiments, one or moresurfactants may be present in an amount of up to 10 wt-%, or up to 5wt-%, based on the total weight of the powder coating composition.

For additives that are in particulate form (e.g., lubricants), theparticles have particle sizes that are no larger than the powder polymerparticles. Typically, they are in the sub-micron range (e.g., less than1 micron, 100 nanometers or less, 50 nanometers or less, or 20nanometers or less), although any suitable size may be employed. Auseful method for determining particle sizes of the optional additives(e.g., lubricants) is laser diffraction particle size analysis.

Method of Making Powder Coating Composition

In certain embodiments, a metal packaging (e.g., a food, beverage,aerosol, or general packaging container, portion thereof, or metalclosure) powder coating composition can be made as follows. In aninitial step, powder polymer particles as described herein are provided.In certain embodiments, these are then combined with one or more chargecontrol agents as described herein. These particles, preferably incontact with one or more charge control agents, are then used as is orwith one or more optional additives as a powder coating composition thatis suitable for use as a metal packaging (e.g., a food, beverage,aerosol, or general packaging container, portion thereof, or metalclosure) powder coating composition as described herein.

The polymer particles may be any suitable polymer particles, including,for example, precipitated polymer particles, polymer particles formed bymethods other than precipitation, or a combination of precipitated andnon-precipitated polymer particles. Any suitable method may be used toform suitably sized precipitated particles of the present disclosure. Incertain embodiments, the method includes providing a carrier (e.g., asolvent) having polymer material dispersed therein, preferably dissolvedtherein, and reducing the solubility of the polymer material in thecarrier (e.g., by cooling the temperature of the carrier, by changingthe composition of the carrier, or by changing the concentration of thepolymer in the carrier) to form precipitated particles. In certainembodiments, the method includes: preparing a mixture of an organicsolvent and a solid crystallizable polymer; heating the mixture to atemperature sufficient to disperse (and preferably dissolve), but notmelt, the solid crystallizable polymer in the organic solvent; andcooling the mixture to form precipitated polymer particles.

In certain embodiments, the powder polymer particles may be preparedusing an emulsion, suspension, solution, or dispersion polymerizationmethod, which are well-known to those skilled in the art. For example, apolymer may be prepared in the form of an aqueous emulsion, suspension,solution, or dispersion using standard techniques and subsequently driedto form particles using any of a variety of techniques including, forexample, spray drying, fluidized bed drying, vacuum drying, radiantdrying, freeze drying, and flash drying, among others. Preferably,drying involves spray drying. Polymer particles produced usingemulsion/suspension/dispersion/solution polymerization are not typicallyconsidered precipitated particles.

In certain embodiments, the powder polymer particles are not prepared bygrinding a polymer to form ground polymer particles (that is, theparticles are not provided as ground particles).

In certain embodiments, the powder polymer particles are provided asagglomerates of primary polymer particles, as described herein, whichmay be prepared using standard techniques well-known to those skilled inthe art. For example, a polymer may be prepared in the form of anaqueous emulsion/dispersion/suspension/solution technique andsubsequently dried using, for example, a spray drying technique. Spraydrying may form agglomerates directly. Spray drying involves theatomization of a liquid feedstock into a spray of droplets andcontacting the droplets with hot air in a drying chamber. The sprays aretypically produced by either rotary (wheel) or nozzle atomizers.Evaporation of moisture from the droplets and formation of dry particlesproceed under controlled temperature and airflow conditions. Powderparticles are typically discharged substantially continuously from thedrying chamber. Operating conditions and dryer design are selectedaccording to the drying characteristics of the product specification.

FIG. 2 shows a suitable spray drying apparatus (for example, the BüchiB290 lab-scale spray dryer) that uses a pressurized gas (1), such ascompressed air or nitrogen, to generate an aerosolized spray of theliquid product via a stainless steel nozzle (2). This spray is coelutedwith a drying gas, such as lab air or nitrogen (3), into a glass dryingtower (4) where the droplets of liquid product are dewatered/desolvatedby the heated air/gas, resulting in solid powder particles that arelargely free of their original solvent or dispersant. A glass cyclone(6) then separates the powder from the heated solvent vapor. If a sampleis to be collected to determine particle size and shape, it is typicallycollected at the collection jar (5) at the bottom of the cyclone (6).Finally, the water/solvent vapor passes through a particulate filter (7)to remove any fine particles before the vapor is exhausted or collected.

Typically, the agglomerated particles formed from a spray dryingtechnique are spherical or substantially spherical. The particle size ofthe agglomerates will typically increase with higher solids content ofthe emulsion/dispersion/suspension/solution and/or with loweratomization pressure in the spray drying nozzles. Secondary drying(e.g., using a fluidized bed) can be done to remove bound water from theagglomerates if desired.

Alternatively, primary particles may be formed, e.g., byemulsion/dispersion/suspension/solution polymerization, or byprecipitation, and subsequently aggregated and/or coalesced to formagglomerated particles using, for example, chemical aggregation ormechanical fusion (e.g., heating above the Tg of a polymer to fuse theprimary particles into an agglomerated particle). Any suitableaggregation process may be used in forming the aggregated dispersionparticles with or without additives (e.g., pigments, lubricants,surfactants).

An example of a particle aggregation process is described in U.S. Pat.No. 9,547,246 (Klier et al.), and includes forming an aqueous dispersionincluding a thermoplastic polymer, a stabilizing agent capable ofpromoting the formation of a stable dispersion or emulsion (e.g., asurfactant), optional additives, and an aggregating agent capable ofcausing complexation (e.g., alkali earth metal or transition metalsalts) in a vessel. The mixture is then stirred until homogenized andheated to a temperature of, for example, about 50° C. The mixture may beheld at such temperature for a period of time to permit aggregation ofthe particles to the desired size. Once the desired size of aggregatedtoner particles is achieved, the pH of the mixture may be adjusted inorder to inhibit further aggregation. The particles may be furtherheated to a temperature of, for example, about 90° C. and the pH loweredin order to enable the particles to coalesce and spherodize. The heateris then turned off and the reactor mixture allowed to cool to roomtemperature, at which point the aggregated and coalesced particles arerecovered and optionally washed and dried. The particle aggregationprocess may also be used starting from an aqueous dispersion including athermoset polymer.

Also, the powder polymer particles of the present disclosure may be madeusing an emulsion aggregation process described in G. E.Kmiecik-Lawrynowicz, DPP2003: IS&Ts International Conference on DigitalProduction Printing and Industrial Applications, pages 211-213, formaking toner particles for high quality digital color printing.

In certain embodiments, the powder polymer particles are combined withone or more charge control agents to form chargeable powder polymerparticles, as described herein. Typically, the method of making a powdercoating composition of the present disclosure includes applying one ormore charge control agents to the powder polymer particles and forming apowder coating composition. The charge control agents (as with any ofthe optional additives described herein) may be added to the powderpolymer particles during their formation (e.g., as in a spray dryingprocess) or subsequent thereto.

In other embodiments, one or more charge control agents are introducedduring, prior to, or both during and prior to, the spray drying processsuch that polymer droplets or nascent forming particles contact chargecontrol agent. While not intending to be bound by theory, the presenceof charge control agent during the spray drying process may beadvantageous for purposes of enhancing mobility of the powder polymerparticles, avoiding or inhibiting clumping of the powder polymerparticles, and/or avoiding or inhibiting sticking of the powder polymerparticles on process equipment.

One or more charge control agents may be added to dried particles (e.g.,after a spray drying process). For example, one or more charge controlagents may be applied to a surface of the powder polymer particles. Thismay involve completely coating the polymer particles with the one ormore charge control agents. It may additionally, or alternatively,involve adhering the one or more charge control agents to the surface ofthe powder polymer particles.

This combination of charge control agents and powder polymer particlesform chargeable particles. For example, the charging of powderparticles, e.g., by friction or induction, can be affected usingprocesses commonly known in photocopying technology or laser printertechnology (which processes are elucidated in, for example, L. B.Schein, Electrophotography and Development Physics, pages 32-244, Volume14, Springer Series in Electrophysics (1988)).

Standard methods of mixing may be used if one or more optional additivesare used with the chargeable particles, which are well-known to thoseskilled in the art. The one or more optional additives may be combinedwith the powder polymer particles, the charge control agent(s), or both.Such optional additives may be added during powder polymer particlepreparation or subsequent thereto. Certain of such additives may beincorporated into the powder polymer particles, coated on the powderpolymer particles, or blended with the powder polymer particles.

The present disclosure also provides methods that include causing themetal packaging powder coating composition to be used on a metalsubstrate of metal packaging. In some cases where multiple parties areinvolved, a first party (e.g., the party that manufactures and/orsupplies the metal packaging powder coating composition) may provideinstructions, recommendations, or other disclosures about the metalpackaging powder coating composition end use to a second party (e.g., ametal coater (e.g., a coil coater for beverage can ends), can maker, orbrand owner). Such disclosures may include, for example, instructions,recommendations, or other disclosures relating to coating a metalsubstrate for subsequent use in forming packaging containers or portionsthereof, coating a metal substrate of pre-formed containers or portionsthereof, preparing powder coating compositions for such uses, cureconditions or process-related conditions for such coatings, or suitabletypes of packaged products for use with resulting coatings. Suchdisclosures may occur, for example, in technical data sheets (TDSs),safety data sheets (SDSs), regulatory disclosures, warranties orwarranty limitation statements, marketing literature or presentations,or on company websites. A first party making such disclosures to asecond party shall be deemed to have caused the metal packaging powdercoating compositions to be used on a metal substrate of metal packaging(e.g., a container or closure) even if it is the second party thatactually applies the composition to a metal substrate in commerce, usessuch coated substrate in commerce on a metal substrate of packagingcontainers, and/or fills such coated containers with product.

Coated Metal Substrate and Method of Coating

The present disclosure also provides a coated metal substrate. The metalsubstrate is preferably of suitable thickness to form a metal food orbeverage container (e.g., can), an aerosol container (e.g., can), ageneral packaging container (e.g., can), or a closure, e.g., for a glassjar. In certain embodiments, the metal substrate has an averagethickness of up to 635 microns, or up to 375 microns. In certainembodiments, the metal substrate has an average thickness of at least125 microns. In embodiments in which a metal foil substrate is employedin forming, e.g., a packaging article, the thickness of the metal foilsubstrate may be even thinner than that described above.

Such metal substrate has a hardened adherent coating disposed on atleast a portion of a surface thereof. The hardened adherent coating isformed from a metal packaging (e.g., a food, beverage, or aerosol can)powder coating composition as described herein with or without one ormore optional additives.

Hardened (e.g., cured) coatings of the disclosure preferably adhere wellto metal (e.g., steel, stainless steel, tin-free steel (TFS), tin-platedsteel, electrolytic tin plate (ETP), aluminum, etc.). They also providehigh levels of resistance to corrosion or degradation that may be causedby prolonged exposure to, for example, food, beverage, or aerosolproducts.

In the context of a hardened adherent coating being disposed “on” asurface or substrate, both coatings applied directly (e.g., virgin metalor pre-treated metal such as electroplated steel) or indirectly (e.g.,on a primer layer) to the surface or substrate are included. Thus, forexample, a coating applied to a pre-treatment layer (e.g., formed from achrome or chrome-free pretreatment) or a primer layer overlying asubstrate constitutes a coating applied on (or disposed on) thesubstrate.

If a steel sheet is used as the metal substrate, the surface treatmentmay comprise one, two, or more kinds of surface treatments such as zincplating, tin plating, nickel plating, electrolytic chromate treatment,chromate treatment, and phosphate treatment. If an aluminum sheet isused as the metal substrate, the surface treatment may include aninorganic chemical conversion treatment such as chromic phosphatetreatment, zirconium phosphate treatment, or phosphate treatment; anorganic/inorganic composite chemical conversion treatment based on acombination of an inorganic chemical conversion treatment with anorganic component as exemplified by a water-soluble resin such as anacrylic resin or a phenol resin, and tannic acid; or an application-typetreatment based on a combination of a water-soluble resin such as anacrylic resin with a zirconium salt.

The hardened adherent coating is preferably continuous. As such, it isfree of pinholes and other coating defects that result in exposedsubstrate, which can lead to (i) unacceptable corrosion of thesubstrate, and can even potentially lead to a hole in the substrate andproduct leakage, and/or (ii) adulteration of the packaged product.Except in embodiments in which coating roughness or texture is desired(e.g., for certain exterior can coatings for aesthetic purposes), thehardened continuous coating is preferably smooth, especially for mostinterior can coatings.

In certain embodiments, the hardened continuous adherent coating has anaverage thickness of up to 100 microns (particularly the coating hastexture), up to 50 microns, up to 25 microns, up to 20 microns, up to 15microns, or up to 10 microns. Interior can coatings are typically lessthan 10 microns thick on average. In certain embodiments, the hardenedadherent coating has an average thickness of at least 1 micron, at least2 microns, at least 3 microns, or at least 4 microns.

The hardened coatings may be used as coatings on any suitable surface,including inside surfaces of metal packaging containers (e.g., food,beverage, or aerosol can bodies, such as three-piece aerosol cans oraluminum monobloc aerosol cans), outside surfaces of such containerbodies, riveted can ends, pull tabs, and combinations thereof. Thehardened coatings may also be used on interior or exterior surfaces ofother packaging containers, or portions thereof, metal closures (e.g.,for glass containers) including bottle crowns, or metered dose inhaler(MDI) cans. Such specific cans, with interior food-contact surfaces,riveted can ends, and pull tabs have specific flexibility requirements,as well as taste, toxicity, and other government regulatoryrequirements.

The powder coating compositions of the present disclosure may also beused on substrates other than rigid metal substrate, includingsubstrates for use in packaging food or beverage products or otherproducts. For example, the powder coating compositions may be used tocoat the interior or exterior surfaces of metal or plastic pouches orother flexible packaging. The powder coating compositions may also beused to coat fiberboard or paperboard (e.g., as employed for Tetra Packcontainers and the like); various plastic containers (e.g.,polyolefins), wraps, or films; metal foils; or glass (e.g., exteriors ofglass bottles to prevent scratching or provide desired color or otheraesthetic effects).

In certain embodiments, the hardened coating includes less than 50 ppm,less than 25 ppm, less than 10 ppm, or less than 1 ppm, extractables, ifany, when tested pursuant to the Global Extraction Test described in theExamples Section. Significantly, such coatings are suitable for use onfood-contact surfaces. Thus, in certain embodiments, a metal packagingcontainer (e.g., a food, beverage, or aerosol can) is provided thatincludes such coated metal substrate, particularly wherein the coatedsurface of the metal substrate forms an interior surface of thecontainer body (which contacts a food, beverage or aerosol product).Alternatively, the coated surface is a surface of a riveted can endand/or a pull tab.

In certain embodiments, the metal substrate is in the form of a planarcoil or sheet. Sheet coating involves applying a coating composition toseparate pieces of a substrate that has been pre-cut into square orrectangular “sheets.” Coil coating is a special application method inwhich coiled metal strips (e.g., aluminum) are unwound and then passedthrough pretreating, coating, and drying equipment before finally beingrewound. It is believed the use of preferred powder coating compositionsof the present disclosure can eliminate the need for the pretreatmentstep employed when using conventional liquid coatings, therebysimplifying the application process and removing cost. Coil coatingallows for very efficient coating of large surface areas in a short timeat high throughput.

For example, in some embodiments, the moving surface of a coil substratein a continuous process is traveling at a line speed of at least 50meters per minute, at least 100 meters per minute, at least 200 metersper minute, or at least 300 meters per minute. Typically, the line speedwill be less than 400 meters per minute. In certain embodiments, thecuring time of the coil coating applied coating compositions is at least6 seconds, at least 10 seconds, or at least 12 seconds, and, in certainembodiments, up to 20 seconds, up to about 25 seconds, or up to about 30seconds. In the context of thermal bakes to cure the coil coating, suchcuring times refer to the residence time in the oven(s). In suchembodiments, the curing process is typically conducted to achieve peakmetal temperatures of 200° C. to 260° C.

Thus, the process of applying a powder coating composition to asubstrate according to the present disclosure is preferably used in acoil-coating process or in a sheet-coating process.

In certain embodiments, the hardened coating is formed from a metalpackaging powder coating composition as described herein with or withoutone or more optional additives, particularly one with the powder polymerparticles described herein and a lubricant. The lubricant may be presentin the hardened coating in the powder polymer particles, on the powderpolymer particles, in another ingredient used to form the powder coatingcomposition (or the hardened coating formed therefrom), or a combinationthereof. Alternatively or additionally, a lubricant as described herein(e.g., carnauba wax, synthetic wax, polytetrafluoroethylene wax,polyethylene wax, polypropylene wax, or a combination thereof) may beapplied to the hardened coating or otherwise disposed on a surface ofthe hardened coating (e.g., via application of another powdercomposition). Similarly, in some embodiments, the lubricant may beapplied in a separate powder layer applied to a first powder layerincluding the polymer particles of the present disclosure prior tocoating cure (i.e., in a so called “dust-on-dust” applicationtechnique). However, when it is incorporated into or on the hardenedcoating, in certain embodiments, a lubricant is present in an amount ofat least 0.1 wt-% (or at least 0.5 wt-%, or at least 1 wt-%), and incertain embodiments, a lubricant is present in an amount of up to 4 wt-%(or up to 3 wt-%, or up to 2 wt-%), based on the total weight of thepowder coating composition (or hardened coating formed therefrom).

In certain embodiments, a hardened coating that includes an amorphouspolymer (and/or semicrystalline polymer with amorphous portions) has aglass transition temperature (Tg) of at least 40° C., at least 50° C.,at least 60° C., or at least 70° C., and in certain embodiments, a Tg ofup to 150° C., up to 130° C., up to 110° C., or up to 100° C. For manypackaging technologies, especially for interior can coatings for moreaggressive products, higher Tg coatings are preferred for corrosionresistance.

In some embodiments, the hardened coating does not have any detectableTg.

In certain embodiments, a hardened coating produced from preferredembodiments of the powder coating composition is capable of passing a 4TT-Bend test when disposed on conventional aluminum beverage can endstock at a conventional average dry film coating weight for an interiorbeverage can coating (e.g., about 2.3 grams per square meter for aninterior soda beverage can coating). A useful T-bend testing procedureis described in ASTM D4145-10 (2010, Reapproved 2018).

Flexibility is especially important for a hardened coating on a metalsubstrate that is fabricated into a metal packaging container (e.g., afood, beverage, or aerosol can) or part of the container (e.g., can),such as a riveted can end or pull tab. Flexibility is important so thatthe coating can deflect with the metal substrate during post-curefabrication steps (e.g., necking and dome reformation), or if the can isdropped from a reasonable height during transport or use.

Flexibility can be determined using the Flexibility Test described inthe Examples Section, which measures the ability of a coated substrateto retain its integrity as it undergoes the formation process necessaryto produce a riveted beverage can end. It is a measure of the presenceor absence of cracks or fractures in the formed end. Preferably, ahardened coating formed from a coating composition described hereinpasses this Flexibility Test. More preferably, a coating composition,when applied to a cleaned and pretreated aluminum panel and subjected toa curative bake for an appropriate duration to achieve a 242° C. peakmetal temperature (PMT) and a dried film thickness of approximately 7.5milligram per square inch and formed into a fully converted 202 standardopening beverage can end, passes less than 5 milliamps of current whilebeing exposed for 4 seconds to an electrolyte solution containing 1% byweight of NaCl dissolved in deionized water.

Method of Coating a Metal Substrate

A method of coating a metal substrate suitable for use in forming metalpackaging (e.g., a metal packaging container such as a food, beverage,aerosol, or general packaging container (e.g., can), or a portionthereof, or a metal closure) is also provided. Such method includes:providing a metal packaging powder coating composition that includesparticles (preferably includes triboelectrically charged particles) asdescribed herein; directing the powder coating composition (preferablytriboelectrically charged powder coating composition) to at least aportion of the metal substrate (e.g., coil or sheet), preferably bymeans of an electromagnetic field (e.g., electric field), or any othersuitable type of applied field; and providing conditions effective forthe powder coating composition to form a hardened continuous coating onat least a portion of the metal substrate.

In certain embodiments, directing the powder coating composition to atleast a portion of the metal substrate, includes: feeding the powdercoating composition to a transporter; and directing the powder coatingcomposition (preferably, triboelectrically charged powder coatingcomposition) from the transporter to at least a portion of the metalsubstrate, by means of an electromagnetic field (e.g., electric field),or any other suitable type of applied field.

In certain embodiments, directing the powder coating compositionincludes directing the powder coating composition (preferably,triboelectrically charged powder coating composition) from thetransporter to at least a portion of the metal substrate by means of anelectric field between the transporter and the metal substrate.

In certain embodiments, directing the powder coating compositionincludes: directing the powder coating composition from the transporterto a transfer medium by means of an electromagnetic field (e.g.,electric field), or any other suitable type of applied field, betweenthe transporter and the transfer medium; and transferring the powdercoating composition from the transfer medium to at least a portion ofthe metal substrate. The transfer may be carried out by applying, forexample, thermal energy (using thermal processing techniques), or otherforces such as electrical, electrostatic, or mechanical forces.

This process is similar to conventional printing processes, but canresult in a substantially (e.g., more than 90%) fully coated substrate,as opposed to a printing process, wherein the coverage is typically muchless (e.g., only 10%) of the substrate. For example, the charging of thepowder particles by friction or induction (known as triboelectriccharging), and the transporting or conveying and the application tosubstrates can be effected using processes commonly known inphotocopying technology or laser printer technology. In particular, anelectric field can be applied using conventional methods, such as acorona discharge or a moving or fixed counter electrode. Such processesare elucidated in, for example, U.S. Pat. No. 6,342,273 (Handels et al.)and L. B. Schein, Electrophotography and Development Physics, pages32-244, Volume 14, Springer Series in Electrophysics (1988).

In certain embodiments, a transfer medium can be used, including, forexample conductive metallic drums. Transfer can be carried out in one ormore steps using multiple transfer media.

In certain embodiments, the powder coating composition includes magneticcarrier particles, although non-magnetic particles may also be used.Suitable magnetic carrier particles have a core of, for example, iron,steel, nickel, magnetite, γ-Fe₂O₃, or certain ferrites such as forexample CuZn, NiZn, MnZn and barium ferrites. Suitable non-magneticcarrier particles include glass, non-magnetic metal, polymer, andceramic material. These particles can be of various shapes, for example,irregular or regular shape, and sizes (e.g., similar to the particlesizes of the powder polymer particles), although spherical,substantially spherical, or potato shaped are preferred.

In certain embodiments, the transporter includes a magnetic roller andthe powder coating composition is conveyed by means of a magnetic rolleras described in, for example, U.S. Pat. No. 4,460,266 (Kopp et al.). Inaddition to a magnetic roller or brush apparatus also useful in thepresent process are, for example, non-magnetic cascade developmentprocesses. In addition, transport by air, for example, powder clouddevelopment, can be used, as described, for example, in U.S. Pat. No.2,725,304 (Landrigan et al.).

FIG. 3A provides a line drawing of an application device capable ofdelivering a powder coating composition to a substrate without the aidof magnetic carrier particles. FIG. 3B provides a line drawing of anapplication device capable of delivering a powder coating composition toa substrate with the aid of a magnetic carrier. During an exemplaryprocess, a uniform charge (either positive or negative) is induced onthe surface of a photo-conductive drum (i.e., a drum having aphoto-conductive coating thereon) by a corona wire. A scanning lightsource (for example, either a laser and mirror assembly or a lightemitting diode (LED) array) converts a computer-generated image into acorresponding pattern on the drum. The photo-conductive coating on thedrum will invert to the opposite charge anywhere the light sourceimpinges on the surface of the drum. Concurrently, a powder coatingcomposition is triboelectrically charged by movement through a series ofaugers and a developer roll. This charge is such that the powder (oncebrought into close contact with the drum) is electrostatically adheredto the areas of the drum that were cross-charged by the scanning lightsource.

In some cases, as demonstrated by FIG. 3A, the powder coatingformulation is developed such that no magnetic carrier particles arerequired. This is typically done by careful selection of charge controland flow control agents discussed elsewhere in this filing. In somecases, as demonstrated by FIG. 3B, magnetic carrier particles (which aregenerally not transferred to the drum or substrate) are employed to helpthe powder coating particles maintain their latent charge fromtriboelectric charging.

One or more corona wires, as shown in FIGS. 3A and 3B, then provide asufficient opposite charge on the metal substrate to transfer the powdercoating particles from the drum to the substrate, in the same patternthat the scanning light source created on the drum. The resultingpattern of powder coating particles on the metal substrate are thenpassed through a thermal, radiation, or induction fuser that causes theparticles to fuse into one another and form a continuous coating.

In certain embodiments, the conditions effective for the powder coatingcomposition to form a hardened coating on at least a portion of themetal substrate includes applying thermal energy (e.g., using aconvection oven or induction coil), UV radiation, IR radiation, orelectron beam radiation to the powder coating composition. Suchprocesses can be carried out in one or more discrete or combined steps.In certain embodiments, the conditions include applying thermal energy.In certain embodiments, applying thermal energy includes using oventemperatures of at least 100° C. or at least 177° C. In certainembodiments, applying thermal energy includes using oven temperatures ofup to 300° C. or up to 250° C. In certain embodiments, applying thermalenergy includes heating the coated metal substrate over a suitable timeperiod to a peak metal temperature (PMT) of at least 177° C. In certainembodiments, applying thermal energy includes heating the coated metalsubstrate over a suitable time period to a peak metal temperature (PMT)of at least 218° C. The time period may be as short as 5 seconds, or aslong as 15 minutes, and preferably less than one minute for forming acoil coating. Preferably, this occurs in a continuous process.

Coated metal substrates of the present disclosure may be drawn andredrawn. Significantly, the coating on the resultant thinned metalsubstrate remains continuous and adherent.

Metal Packaging and Method of Making

The present disclosure also provides metal packaging (e.g., a metalpackaging container such as a food, beverage, aerosol, or generalpackaging container (e.g., can), a portion thereof, or a metal closure)that includes a coated metal substrate as described herein. In certainembodiments, the coated surface of the metal substrate forms an interiorsurface of the container (e.g., can) or closure (although it can form anexterior surface). In certain embodiments, the coated surface of themetal substrate is a surface of a riveted can end, a pull tab, and/or acan body. In certain embodiments, the metal packaging container (e.g.,food, beverage, or aerosol can) is filled with a food, beverage, oraerosol product.

In certain embodiments, a method of making metal packaging (e.g., ametal packaging container such as a food, beverage, aerosol, or generalpackaging container (e.g., can), a portion thereof, or a metal closurefor a container such as a metal can or glass jar) is provided. Themethod includes: providing a metal substrate (e.g., coil or sheet)having a hardened continuous adherent coating disposed on at least aportion of a surface thereof, wherein: the metal substrate has anaverage thickness of up to 635 microns; the hardened continuous adherentcoating is formed from a metal packaging powder coating composition;wherein the powder coating composition comprises powder polymerparticles comprising a polymer having a number average molecular weightof at least 2000 Daltons, wherein the powder polymer particles have aparticle size distribution having a D50 of less than 25 microns; andforming the substrate (e.g., by stamping) into at least a portion of ametal packaging container (e.g., food, beverage, aerosol, or generalpackaging can) or a portion thereof, or a metal closure for a container(e.g., metal can or glass jar).

For example, two-piece or three-piece cans or portions thereof such asstamped riveted beverage can ends (e.g., soda or beer cans) with ahardened coating formed from the powder coating composition describedherein disposed thereon can be formed using such a method. Standardfabrication techniques, e.g., stamping, can be used.

In certain embodiments, the coated surface of the metal substrate formsan interior surface of a can. In certain embodiments, the coated surfaceof the metal substrate is a surface of a riveted can end, a pull tab,and/or a can body. In certain embodiments, the can is filled with afood, beverage, or aerosol product.

EXEMPLARY EMBODIMENTS Embodiments A: Metal Packaging Powder CoatingComposition

Embodiment A-1 is a metal packaging (e.g., a food, beverage, aerosol, orgeneral packaging container (e.g., can), portion thereof, or metalclosure) powder coating composition comprising: powder polymer particles(preferably, spray dried powder polymer particles) comprising a polymerhaving a number average molecular weight of at least 2000 Daltons,wherein the powder polymer particles have a particle size distributionhaving a D50 of less than 25 microns; and one or more charge controlagents in contact with the powder polymer particles.

Embodiment A-2 is the powder coating composition of Embodiment A-1,wherein the powder polymer particles have a particle size distributionhaving a D50 of less than 20 microns, less than 15 microns, or less than10 microns.

Embodiment A-3 is the powder coating composition of Embodiment A-1 orA-2, wherein the powder polymer particles have a particle sizedistribution having a D90 of less than 25 microns, less than 20 microns,less than 15 microns, or less than 10 microns.

Embodiment A-4 is the powder coating composition of any of the precedingembodiments, wherein the powder polymer particles have a particle sizedistribution having a D95 of less than 25 microns, less than 20 microns,less than 15 microns, or less than 10 microns.

Embodiment A-5 is the powder coating composition of any of the precedingembodiments, wherein the powder polymer particles have a particle sizedistribution having a D99 of less than 25 microns, less than 20 microns,less than 15 microns, or less than 10 microns.

Embodiment A-6 is the powder coating composition of any of the precedingembodiments, wherein the powder polymer particles have a particle sizedistribution having a D50 (in certain embodiments, a D90, D95, or a D99)of greater than 1 micron, greater than 2 microns, greater than 3microns, or greater than 4 microns.

Embodiment A-7 is the powder coating composition of any of the precedingembodiments, wherein the powder coating composition as a whole has aparticle size distribution having a D50 (preferably, a D90, D95, or aD99) of less than 25 microns, less than 20 microns, less than 15microns, or less than 10 microns, and optionally also a D90 of less than25 microns, less than 20 microns, less than 15 microns, or less than 10microns.

Embodiment A-8 is the powder coating composition of any of the precedingembodiments comprising at least 50 wt-%, at least 60 wt-%, at least 70wt-%, at least 80 wt-%, or at least 90 wt-% of the powder polymerparticles, based on the total weight of the powder coating composition.

Embodiment A-9 is the powder coating composition of any of the precedingembodiments comprising up to 100 wt-%, up to 99.99 wt-%, up to 95 wt-%,or up to 90 wt-%, of the powder polymer particles, based on the totalweight of the powder coating composition.

Embodiment A-10 is the powder coating composition of any of thepreceding embodiments, wherein the one or more charge control agents arepresent in an amount of at least 0.01 wt-%, at least 0.1 wt-%, or atleast 1 wt-%, based on the total weight of the powder coatingcomposition (e.g., the charge control agent(s) and powder polymerparticles).

Embodiment A-11 is the powder coating composition of any of thepreceding embodiments, wherein the one or more charge control agents arepresent in an amount of up to 10 wt-%, up to 9 wt-%, up to 8 wt-%, up to7 wt-%, up to 6 wt-%, up to 5 wt-%, up to 4 wt-%, or up to 3 wt-%, basedon the total weight of the powder coating composition (e.g., the chargecontrol agent(s) and powder polymer particles).

Embodiment A-12 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles arechemically produced (as opposed to mechanically produced (e.g., ground)polymer particles).

Embodiment A-13 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles have a shapefactor of 100-140 (spherical and potato shaped), and preferably 120-140(e.g., potato shaped).

Embodiment A-14 is the powder coating composition of any of thepreceding embodiments, wherein the powder coating composition as a whole(i.e., the overall composition) has a shape factor of 100-140 (sphericaland potato shaped), and preferably 120-140 (e.g., potato shaped).

Embodiment A-15 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles have acompressibility index of 1 to 20 (or 1 to 10, 11 to 15, or 16 to 20).

Embodiment A-16 is the powder coating composition of any of thepreceding embodiments, wherein the powder coating composition as a wholehas a compressibility index of 1 to 20 (or 1 to 10, 11 to 15, or 16 to20).

Embodiment A-17 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles have aHaussner Ratio of 1.00 to 1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19to 1.25).

Embodiment A-18 is the powder coating composition of any of thepreceding embodiments, wherein the powder coating composition as a wholehas a Haussner Ratio of 1.00 to 1.25 (or 1.00 to 1.11, 1.12 to 1.18, or1.19 to 1.25).

Embodiment A-19 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles comprise athermoplastic polymer.

Embodiment A-20 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles comprise apolymer having a melt flow index greater than 15 grams/10 minutes,greater than 50 grams/10 minutes, or greater than 100 grams/10 minutes.

Embodiment A-21 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles comprise apolymer having a melt flow index of up to 200 grams/10 minutes, or up to150 grams/10 minutes.

Embodiment A-22 is the powder coating composition of any of thepreceding embodiments, wherein the powder coating composition as a wholeexhibits a melt flow index greater than 15 grams/10 minutes, greaterthan 50 grams/10 minutes, or greater than 100 grams/10 minutes.

Embodiment A-23 is the powder coating composition of any of thepreceding embodiments, wherein the powder coating composition as a wholeexhibits a melt flow index of up to 200 grams/10 minutes, or up to 150grams/10 minutes.

Embodiment A-24 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles comprise athermoset polymer.

Embodiment A-25 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles comprise anamorphous polymer having a glass transition temperature (Tg) of at least0° C., at least 30° C., at least 40° C., at least 50° C., at least 60°C., or at least 70° C.

Embodiment A-26 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles comprise anamorphous polymer having a Tg of up to 150° C., up to 125° C., up to110° C., up to 100° C., or up to 80° C. Embodiment A-27 is the powdercoating composition of any of the preceding embodiments, wherein thepowder polymer particles comprise a crystalline or semi-crystallinepolymer having a melting point of at least 40° C.

Embodiment A-28 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles comprise acrystalline or semi-crystalline polymer having a melting point of up to130° C.

Embodiment A-29 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles comprise apolymer selected from a polyacrylic, polyether, polyolefin, polyester,polyurethane, polycarbonate, polystyrene, or a combination thereof(i.e., copolymer or mixture thereof such as acrylonitrile butadienestyrene). Preferably, the polymer is selected from a polyacrylic,polyether, polyolefin, polyester, or a combination thereof.

Embodiment A-30 is the powder coating composition of any of thepreceding embodiments, wherein the polymer Mn is at least 5,000 Daltons,at least 10,000 Daltons, or at least 15,000 Daltons.

Embodiment A-31 is the powder coating composition of any of thepreceding embodiments, wherein the polymer Mn is up to 10,000,000Daltons, up to 1,000,000 Daltons, up to 100,000 Daltons, or up to 20,00Daltons.

Embodiment A-32 is the powder coating composition of any of thepreceding embodiments, wherein the polymer has a polydispersity index(Mw/Mn) of less than 4, less than 3, less than 2, or less than 1.5.

Embodiment A-33 is the powder coating composition of any of thepreceding embodiments, wherein the one or more charge control agents aredisposed on a surface of the powder polymer particles (in certainembodiments, the polymer particles are at least substantially coated, oreven completely coated, with charge control agent).

Embodiment A-34 is the powder coating composition of any of thepreceding embodiments, wherein the one or more charge control agentsenable the powder polymer particles to efficiently accept a charge tofacilitate application to substrate.

Embodiment A-35 is the powder coating composition of Embodiment A-34,wherein the one or more charge control agents provide a triboelectriccharge to the powder polymer particles by friction, during applicationto a substrate, thereby forming charged powder polymer particles.

Embodiment A-36 is the powder coating composition of any of thepreceding embodiments, wherein the one or more charge control agentscomprise particles having particle sizes in the sub-micron range (e.g.,less than 1 micron, 100 nanometers or less, 50 nanometers or less, or 20nanometers or less).

Embodiment A-37 is the powder coating composition of any of thepreceding embodiments, wherein the one or more charge control agentscomprise inorganic particles.

Embodiment A-38 is the powder coating composition of any of thepreceding embodiments, wherein the one or more charge control agentscomprise hydrophilic fumed aluminum oxide particles, hydrophilicprecipitated sodium aluminum silicate particles, metal carboxylate andsulfonate particles, quaternary ammonium salts (e.g., quaternaryammonium sulfate or sulfonate particles), polymers containing pendantquaternary ammonium salts, ferromagnetic particles, transition metalparticles, nitrosine or azine dyes, copper phthalocyanine pigments,metal complexes of chromium, zinc, aluminum, zirconium, calcium, orcombinations thereof.

Embodiment A-39 is the powder coating composition of any of thepreceding embodiments further comprising one or more optional additivesselected from lubricants, adhesion promoters, crosslinkers, catalysts,colorants (e.g., pigments or dyes), ferromagnetic particles, degassingagents, levelling agents, wetting agents, surfactants, flow controlagents, heat stabilizers, anti-corrosion agents, adhesion promoters,inorganic fillers, metal driers, and combinations thereof.

Embodiment A-40 is the powder coating composition of Embodiment A-39further comprising one or more lubricants.

Embodiment A-41 is the powder coating composition of Embodiment A-40,wherein the one or more lubricants are present in the powder coatingcomposition in an amount of at least 0.1 wt-%, at least 0.5 wt-%, or atleast 1 wt-%, based on the total weight of the powder coatingcomposition.

Embodiment A-42 is the powder coating composition of Embodiment A-40 orA-41, wherein the one or more lubricants are present in the powdercoating composition in an amount of up to 4 wt-%, up to 3 wt-%, or up to2 wt-%, based on the total weight of the powder coating composition.

Embodiment A-43 is the powder coating composition of any of EmbodimentsA-39 through A-42 further comprising one or more crosslinkers and/orcatalysts.

Embodiment A-44 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles compriseagglomerates (i.e., clusters) of primary polymer particles.

Embodiment A-45 is the powder coating composition of Embodiment A-44,wherein the agglomerates have a particle size of 1 micron to 25 microns.

Embodiment A-46 is the powder coating composition of Embodiment A-44 orA-45, wherein and the primary polymer particles have a primary particlesize of 0.05 micron to 8 microns.

Embodiment A-47 is the powder coating composition of any of thepreceding embodiments, wherein the powder polymer particles are spraydried powder polymer particles.

Embodiment A-48 is the powder coating composition of any of thepreceding embodiments which is substantially free of each of bisphenolA, bisphenol F, and bisphenol S, structural units derived therefrom, orboth.

Embodiment A-49 is the powder coating composition of any of thepreceding embodiments which is substantially free of all bisphenolcompounds, structural units derived therefrom, or both, except forTMBPF.

Embodiment A-50 is the powder coating composition of any of thepreceding embodiments which forms a hardened coating that includes lessthan 50 ppm, less than 25 ppm, less than 10 ppm, or less than 1 ppm,extractables, if any, when tested pursuant to the Global ExtractionTest.

Embodiment A-51 is the powder coating composition of any of thepreceding embodiments which forms a hardened coating that adheres to asubstrate, such as a metal substrate, according to the Adhesion Testwith an adhesion rating of 9 or 10, preferably 10.

Embodiment A-52 is the powder coating composition of any of thepreceding embodiments which forms a continuous hardened coating that isfree of pinholes and other coating defects that result in exposedsubstrate. Such film imperfections/failures can be indicated by acurrent flow measured in milliamps (mA) using the Flat Panel ContinuityTest described in the Examples Section.

Embodiment A-53 is the powder coating composition of any of thepreceding embodiments which, when applied to a cleaned and pretreatedaluminum panel and subjected to a curative bake for an appropriateduration to achieve a 242° C. peak metal temperature (PMT) and a driedfilm thickness of approximately 7.5 milligram per square inch and formedinto a fully converted 202 standard opening beverage can end, passesless than 5 milliamps of current while being exposed for 4 seconds to anelectrolyte solution containing 1% by weight of NaCl dissolved indeionized water.

Embodiments B: Method of Making a Metal Packaging Powder CoatingComposition

Embodiment B-1 is a method of making a metal packaging (e.g., a food,beverage, aerosol, or general packaging container, portion thereof, ormetal closure) powder coating composition, the method comprising:providing powder polymer particles (preferably, spray dried powderpolymer particles) comprising a polymer having a number averagemolecular weight of at least 2000 Daltons; wherein the powder polymerparticles have a particle size distribution having a D50 of less than 25microns; and applying one or more charge control agents to the powderpolymer particles and forming a powder coating composition; wherein thepowder coating composition is a metal packaging (e.g., a food, beverage,aerosol, or general packaging container, portion thereof, or metalclosure) powder coating composition.

Embodiment B-2 is the method of Embodiment B-1, wherein the powderpolymer particles have a particle size distribution having a D50 of lessthan 20 microns, less than 15 microns, or less than 10 microns.

Embodiment B-3 is the method of Embodiment B-1 or B-2, wherein thepowder polymer particles have a particle size distribution having a D90of less than 25 microns, less than 20 microns, less than 15 microns, orless than 10 microns.

Embodiment B-4 is the method of any of the preceding embodiments,wherein the powder polymer particles have a particle size distributionhaving a D95 of less than 25 microns, less than 20 microns, less than 15microns, or less than 10 microns.

Embodiment B-5 is the method of any of the preceding embodiments,wherein the powder polymer particles have a particle size distributionhaving a D99 of less than 25 microns, less than 20 microns, less than 15microns, or less than 10 microns.

Embodiment B-6 is the method of any of the preceding embodiments,wherein the powder coating composition comprises at least 50 wt-%, atleast 60 wt-%, at least 70 wt-%, at least 80 wt-%, or at least 90 wt-%of the powder polymer particles, based on the total weight of the powdercoating composition.

Embodiment B-7 is the method of any of the preceding embodiments,wherein the powder coating composition comprises up to 100 wt-%, up to99.99 wt-%, up to 95 wt-%, or up to 90 wt-%, of the powder polymerparticles, based on the total weight of the powder coating composition.

Embodiment B-8 is the method of any of the preceding embodiments,wherein the powder coating composition comprises at least 0.01 wt-%, atleast 0.1 wt-%, or at least 1 wt-%, of the one or more charge controlagents, based on the total weight of the powder coating composition.

Embodiment B-9 is the method of any of the preceding embodiments,wherein the powder coating composition comprises up to 10 wt-%, up to 9wt-%, up to 8 wt-%, up to 7 wt-%, up to 6 wt-%, up to 5 wt-%, up to 4wt-%, or up to 3 wt-%, of the one or more charge control agents, basedon the total weight of the powder coating composition.

Embodiment B-10 is the method of any of the preceding embodiments,wherein the powder polymer particles are chemically produced (as opposedto mechanically produced (e.g., ground) polymer particles).

Embodiment B-11 is the method of any of the preceding embodiments,wherein the powder polymer particles have a shape factor of 100-140(spherical and potato shaped) (or 120-140 (e.g., potato shaped)).

Embodiment B-12 is the method of any of the preceding embodiments,wherein the powder polymer particles have a compressibility index of 1to 20 (or 1 to 10, 11 to 15, or 16 to 20).

Embodiment B-13 is the method of any of the preceding embodiments,wherein the powder polymer particles have a Haussner Ratio of 1.00 to1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25).

Embodiment B-14 is the method of any of the preceding embodiments,wherein providing the powder polymer particles comprises preparing amixture of an organic solvent and a solid crystallizable polymer;heating the mixture to a temperature sufficient to disperse, but notmelt, the solid crystallizable polymer in the organic solvent; andcooling the mixture to form precipitated polymer particles.

Embodiment B-15 is the method of any of Embodiments B-1 through B-13,wherein providing the powder polymer particles comprises forming anaqueous polymeric emulsion, suspension, solution, or dispersion; anddrying the aqueous polymeric emulsion, suspension, solution, ordispersion to form powder polymer particles.

Embodiment B-16 is the method of Embodiment B-15, wherein dryingcomprises spray drying, fluidized bed drying, vacuum drying, radiantdrying, freeze drying, or flash drying.

Embodiment B-17 is the method of Embodiment B-16, wherein dryingcomprises spray drying.

Embodiment B-18 is the method of Embodiment B-17, wherein applying theone or more charge control agents comprises introducing one or morecharge control agents during, prior to, or both during and prior to, thespray drying process such that polymer droplets or nascent formingparticles contact charge control agent.

Embodiment B-19 is the method of any of Embodiments B-1 through B-17,wherein applying the one or more charge control agents comprise applyingone or more charge control agents to dry powder polymer particles.

Embodiment B-20 is the method of any of the preceding embodiments,wherein applying the one or more charge control agents comprisesapplying one or more charge control agents to a surface of the powderpolymer particles.

Embodiment B-21 is the method of Embodiment B-20, wherein applying oneor more charge control agents to a surface of the powder polymerparticles comprises completely coating the polymer particles with one ormore charge control agents.

Embodiment B-22 is the method of Embodiment B-20 or B-21, whereinapplying one or more charge control agents to a surface of the powderpolymer particles comprises adhering the one or more charge controlagents to the surface of the powder polymer particles.

Embodiment B-23 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a thermoplastic polymer.

Embodiment B-24 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a polymer having a meltflow index greater than 15 grams/10 minutes, greater than 50 grams/10minutes, or greater than 100 grams/10 minutes, and in certainembodiments, a melt flow index of up to 200 grams/10 minutes, or up to150 grams/minutes.

Embodiment B-25 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise an amorphous polymerhaving a glass transition temperature (Tg) of at least 0° C., at least30° C., at least 40° C., at least 50° C., at least 60° C., or at least70° C.

Embodiment B-26 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise an amorphous polymerhaving a Tg of up to 150° C., up to 125° C., up to 110° C., up to 100°C., or up to 80° C.

Embodiment B-27 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a crystalline orsemi-crystalline polymer having a melting point of at least 40° C.

Embodiment B-28 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a crystalline orsemi-crystalline polymer having a melting point of up to 130° C.

Embodiment B-29 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a polymer selected from anacrylic (i.e., acrylate), polyether, polyolefin, polyester,polyurethane, polyurethane, polycarbonate, polystyrene, or a combinationthereof (i.e., copolymer or mixture thereof such as acrylonitrilebutadiene styrene).

Embodiment B-30 is the method of any of the preceding embodiments,wherein the polymer Mn is at least 5,000 Daltons, at least 10,000Daltons, or at least 15,000 Daltons.

Embodiment B-31 is the method of any of the preceding embodiments,wherein the polymer Mn is up to 10,000,000 Daltons, up to 1,000,000Daltons, up to 100,000 Daltons, or up to 20,00 Daltons.

Embodiment B-32 is the method of any of the preceding embodiments,wherein the polymer has a polydispersity index (Mw/Mn) of less than 4,less than 3, less than 2, or less than 1.5.

Embodiment B-33 is the method of any of the preceding embodiments,wherein the one or more charge control agents enable the powder polymerparticles to efficiently accept a triboelectric charge to facilitateapplication to a substrate.

Embodiment B-34 is the method of any of the preceding embodiments,wherein the one or more charge control agents comprise particles havingparticle sizes in the sub-micron range (e.g., less than 1 micron, 100nanometers or less, 50 nanometers or less, or 20 nanometers or less).

Embodiment B-35 is the method of any of the preceding embodiments,wherein the one or more charge control agents comprise inorganicparticles.

Embodiment B-36 is the method of any of the preceding embodiments,wherein the one or more charge control agents comprise hydrophilic fumedaluminum oxide particles, hydrophilic precipitated sodium aluminumsilicate particles, metal carboxylate and sulfonate particles,quaternary ammonium salts (e.g., quaternary ammonium sulfate orsulfonate particles), polymers containing pendant quaternary ammoniumsalts, ferromagnetic particles, transition metal particles, nitrosine orazine dyes, copper phthalocyanine pigments, metal complexes of chromium,zinc, aluminum, zirconium, calcium, or combinations thereof.

Embodiment B-37 is the method of any of the preceding embodimentsfurther comprising adding one or more optional additives to the powdercoating composition.

Embodiment B-38 is the method of Embodiment B-37, wherein adding one ormore optional additives comprises combining the one or more optionaladditives with the powder polymer particles, the charge controlagent(s), or both.

Embodiment B-39 is the method of Embodiment B-38, wherein adding one ormore optional additives comprises incorporating the one or more optionaladditives into the powder polymer particles, coating the one or moreoptional additives on the powder polymer particles, or blending the oneor more optional additives with the powder polymer particles.

Embodiment B-40 is the method of Embodiment B-39, wherein adding one ormore optional additives comprises adding the one or more optionaladditives during powder polymer particle preparation.

Embodiment B-41 is the method of any of Embodiments B-37 through B-40,wherein the one or more optional additives are selected from lubricants,adhesion promoters, crosslinkers, catalysts, colorants (e.g., pigmentsor dyes), ferromagnetic particles, degassing agents, levelling agents,wetting agents, surfactants, flow control agents, heat stabilizers,anti-corrosion agents, adhesion promoters, inorganic fillers, metaldriers, and combinations thereof.

Embodiment B-42 is the method of Embodiment B-41 further comprising oneor more lubricants.

Embodiment B-43 is the method of Embodiment B-42, wherein the one ormore lubricants are present in the powder coating composition in anamount of at least 0.1 wt-%, at least 0.5 wt-%, or at least 1 wt-%,based on the total weight of the powder coating composition.

Embodiment B-44 is the method of Embodiment B-41 or B-42, wherein theone or more lubricants are present in the powder coating composition inan amount of up to 4 wt-%, up to 3 wt-%, or up to 2 wt-%, based on thetotal weight of the powder coating composition.

Embodiment B-45 is the method of any of Embodiments B-41 through B-44further comprising one or more crosslinkers and/or catalysts.

Embodiment B-46 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise agglomerates (i.e.,clusters) of primary polymer particles.

Embodiment B-47 is the method of Embodiment B-46, wherein theagglomerates have a particle size of 1 micron to 25 microns, and theprimary polymer particles have a primary particle size of 0.05 micron to8 microns.

Embodiment B-48 is the method of any of the preceding embodiments,wherein the powder coating composition is substantially free of each ofbisphenol A, bisphenol F, and bisphenol S, structural units derivedtherefrom, or both.

Embodiment B-49 is the method of any of the preceding embodiments,wherein the powder coating composition is substantially free of allbisphenol compounds, structural units derived therefrom, or both, exceptfor TMBPF.

Embodiment B-50 is the method of any of the preceding embodiments,wherein the powder coating composition forms a coating that includesless than 50 ppm, less than 25 ppm, less than 10 ppm, or less than 1ppm, extractables, if any, when tested pursuant to the Global ExtractionTest.

Embodiment B-51 is the method of any of the preceding embodiments,wherein the powder coating composition forms a coating that adheres to asubstrate, such as a metal substrate, according to the Adhesion Testwith an adhesion rating of 9 or 10, preferably 10.

Embodiment B-52 is the method of any of the preceding embodiments,wherein the powder coating composition forms a continuous hardenedcoating that is free of pinholes and other coating defects that resultin exposed substrate. Such film imperfections/failures can be indicatedby a current flow measured in milliamps (mA) using the Flat PanelContinuity Test described in the Examples Section.

Embodiment B-53 is the method of any of the preceding embodiments,wherein the powder coating composition which, when applied to a cleanedand pretreated aluminum panel and subjected to a curative bake for anappropriate duration to achieve a 242° C. peak metal temperature (PMT)and a dried film thickness of approximately 7.5 milligram per squareinch and formed into a fully converted 202 standard opening beverage canend, passes less than 5 milliamps of current while being exposed for 4seconds to an electrolyte solution containing 1% by weight of NaCldissolved in deionized water.

Embodiment B-54 is the method of any of the preceding embodimentsfurther comprising causing the metal packaging powder coatingcomposition to be used on a metal substrate of metal packaging.

Embodiments C: Method of Coating a Metal Substrate

Embodiment C-1 is a method of coating a metal substrate suitable for usein forming metal packaging (e.g., a metal packaging container such as afood, beverage, or aerosol container (e.g., can), a portion thereof, ormetal closure), the method comprising: providing a metal packagingpowder coating composition, wherein the powder coating compositioncomprises powder polymer particles (preferably, spray dried powderpolymer particles) comprising a polymer having a number averagemolecular weight of at least 2000 Daltons, wherein the powder polymerparticles have a particle size distribution having a D50 of less than 25microns; directing the powder coating composition to at least a portionof the metal substrate, wherein the metal substrate has an averagethickness of up to 635 microns; and providing conditions effective forthe powder coating composition to form a hardened continuous adherentcoating on at least a portion of the metal substrate, wherein thehardened continuous adherent coating has an average thickness of up to100 microns (e.g., for textured can exteriors) (preferably up to 50microns, more preferably up to 25 microns, even more preferably up to 20microns, still more preferably up to 15 microns, and most preferably upto 10 microns).

Embodiment C-2 is the method of Embodiment C-1, wherein the powdercoating composition comprises at least 50 wt-%, at least 60 wt-%, atleast 70 wt-%, at least 80 wt-%, or at least 90 wt-% of the powderpolymer particles, based on the total weight of the powder coatingcomposition.

Embodiment C-3 is the method of Embodiment C-1 or C-2, wherein thepowder coating composition comprises up to 100 wt-%, up to 99.99 wt-%,up to 95 wt-%, or up to 90 wt-%, of the powder polymer particles, basedon the total weight of the powder coating composition.

Embodiment C-4 is the method of any of the preceding embodiments,wherein the powder coating composition comprises one or more chargecontrol agents in contact with the powder polymer particles.

Embodiment C-5 is the method of Embodiment C-4, wherein the powdercoating composition comprises at least 0.01 wt-%, at least 0.1 wt-%, orat least 1 wt-%, of the one or more charge control agents, based on thetotal weight of the powder coating composition.

Embodiment C-6 is the method of Embodiment C-4 or C-5, wherein thepowder coating composition comprises up to 10 wt-%, up to 9 wt-%, up to8 wt-%, up to 7 wt-%, up to 6 wt-%, up to 5 wt-%, up to 4 wt-%, or up to3 wt-%, of the one or more charge control agents, based on the totalweight of the powder coating composition.

Embodiment C-6 is the method of any of the previous embodiments, whereindirecting the powder coating composition comprises directing the powdercoating composition (preferably, triboelectrically charged powdercoating composition) to at least a portion of the metal substrate, bymeans of an electromagnetic field (e.g., an electric field), or anyother suitable type of applied field.

Embodiment C-7 is the method of Embodiment C-6, wherein directing thepowder coating composition comprises directing the powder coatingcomposition to at least a portion of the metal substrate, by means of anelectric field.

Embodiment C-8 is the method of any of the preceding embodiments,wherein directing the powder coating composition to at least a portionof the metal substrate comprises: feeding the powder coating compositionto a transporter; and directing the powder coating composition from thetransporter to at least a portion of the metal substrate, by means of anelectromagnetic field.

Embodiment C-9 is the method of embodiment C-8, wherein directing thepowder coating composition from the transporter comprises directing thepowder coating composition from the transporter to at least a portion ofthe metal substrate by means of an electric field between thetransporter and the metal substrate.

Embodiment C-10 is the method of Embodiment C-8 or C-9, whereindirecting the powder coating composition from the transporter comprises:directing the powder coating composition from the transporter to atransfer medium by means of an electric field between the transporterand the transfer medium; and transferring the powder coating compositionfrom the transfer medium to at least a portion of the metal substrate.

Embodiment C-11 is the method of Embodiment C-10, wherein the transfermedium comprises a conductive metallic drum.

Embodiment C-12 is the method of Embodiment C-10 or C-11, whereintransferring the powder coating composition from the transfer medium toat least a portion of the metal substrate comprises applying thermalenergy, or electrical, electrostatic, or mechanical forces.

Embodiment C-13 is the method of any of embodiments C-8 through C-12,wherein the transporter comprises a magnetic roller, and the powdercoating composition comprises magnetic carrier particles.

Embodiment C-14 is the method of any of the preceding embodiments,wherein providing conditions effective for the powder coatingcomposition to form a hardened coating on at least a portion of themetal substrate comprises applying thermal energy (e.g., using aconvection oven or induction coil), UV radiation, IR radiation, orelectron beam radiation to the powder coating composition.

Embodiment C-15 is the method of embodiment C-14, wherein the conditionscomprise applying thermal energy.

Embodiment C-16 is the method of embodiment C-15, wherein applyingthermal conditions comprise applying thermal energy at a temperature ofat least 100° C. or at least 177° C.

Embodiment C-17 is the method of embodiment C-15 of C-16, whereinapplying thermal conditions comprise applying thermal energy at atemperature of up to 300° C. or up to 250° C.

Embodiment C-18 is the method of any of the preceding embodiments,wherein the metal substrate comprises steel, stainless steel, tin-freesteel (TFS), tin-plated steel, electrolytic tin plate (ETP), oraluminum.

Embodiment C-19 is the method of any of the preceding embodiments,wherein the metal substrate has an average thickness of up to 375microns.

Embodiment C-20 is the method of any of the preceding embodiments,wherein the metal substrate has an average thickness of at least 125microns.

Embodiment C-21 is the method of any of the preceding embodiments,wherein the hardened continuous adherent coating has an averagethickness of up to 25 microns, up to 20 microns, up to 15 microns, or upto 10 microns.

Embodiment C-22 is the method of any of the preceding embodiments,wherein the hardened adherent coating has an average thickness of atleast 1 micron, at least 2 microns, at least 3 microns, or at least 4microns.

Embodiment C-23 is the method of any of the preceding embodiments,wherein the powder polymer particles have a particle size distributionhaving a D50 of less than 20 microns, less than 15 microns, or less than10 microns.

Embodiment C-24 is the method of any of the preceding embodiments,wherein the powder polymer particles have a particle size distributionhaving a D90 of less than 25 microns, less than 20 microns, less than 15microns, or less than 10 microns.

Embodiment C-25 is the method of any of the preceding embodiments,wherein the powder polymer particles are chemically produced (as opposedto mechanically produced (e.g., ground) polymer particles).

Embodiment C-26 is the method of any of the preceding embodiments,wherein the powder polymer particles have a shape factor of 100-140(spherical and potato shaped) (or 120-140 (e.g., potato shaped)).

Embodiment C-27 is the method of any of the preceding embodiments,wherein the powder polymer particles have a compressibility index of 1to 20 (or 1 to 10, 11 to 15, or 16 to 20), and a Haussner Ratio of 1.00to 1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25).

Embodiment C-28 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a thermoplastic polymer.

Embodiment C-29 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a polymer having a meltflow index greater than 15 grams/10 minutes, greater than 50 grams/10minutes, or greater than 100 grams/10 minutes, and in certainembodiments, a melt flow index of up to 200 grams/10 minutes, or up to150 grams/10 minutes.

Embodiment C-30 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise an amorphous polymerhaving a glass transition temperature (Tg) of at least 0° C., at least30° C., at least 40° C., at least 50° C., at least 60° C., or at least70° C.

Embodiment C-31 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise an amorphous polymerhaving a Tg of up to 150° C., up to 125° C., up to 110° C., up to 100°C., or up to 80° C. Embodiment C-32 is the method of any of thepreceding embodiments, wherein the hardened coating does not have anydetectable Tg.

Embodiment C-33 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a crystalline orsemi-crystalline polymer having a melting point of at least 40° C. andup to 130° C.

Embodiment C-34 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a polymer selected from apolyacrylic, polyether, polyolefin, polyester, polyurethane,polycarbonate, polystyrene, or a combination thereof (i.e., copolymer ormixture thereof such as acrylonitrile butadiene styrene). Preferably,the polymer is selected from a polyacrylic, polyether, polyolefin,polyester, or a combination thereof.

Embodiment C-35 is the method of any of the preceding embodiments,wherein the polymer Mn is at least 5,000 Daltons, at least 10,000Daltons, or at least 15,000 Daltons.

Embodiment C-36 is the method of any of the preceding embodiments,wherein the polymer Mn is up to 10,000,000 Daltons, up to 1,000,000Daltons, up to 100,000 Daltons, or up to 20,00 Daltons.

Embodiment C-37 is the method of any of the preceding embodiments,wherein the polymer has a polydispersity index (Mw/Mn) of less than 4,less than 3, less than 2, or less than 1.5.

Embodiment C-38 is the method of any of Embodiments C-4 through C-37,wherein the one or more charge control agents enable the powder polymerparticles to efficiently accept a triboelectric charge to facilitateapplication to a substrate.

Embodiment C-39 is the method of any of Embodiments C-4 through C-38,wherein the one or more charge control agents comprise particles havingparticle sizes in the sub-micron range (e.g., less than 1 micron, 100nanometers or less, 50 nanometers or less, or 20 nanometers or less).

Embodiment C-40 is the method of any of Embodiments C-4 through C-39,wherein the one or more charge control agents comprise inorganicparticles.

Embodiment C-41 is the method of any of Embodiments C-4 through C-40,wherein the one or more charge control agents comprise hydrophilic fumedaluminum oxide particles, hydrophilic precipitated sodium aluminumsilicate particles, metal carboxylate and sulfonate particles,quaternary ammonium salts (e.g., quaternary ammonium sulfate orsulfonate particles), polymers containing pendant quaternary ammoniumsalts, ferromagnetic particles, transition metal particles, nitrosine orazine dyes, copper phthalocyanine pigments, metal complexes of chromium,zinc, aluminum, zirconium, calcium, or combinations thereof.

Embodiment C-42 is the method of any of the preceding embodiments,wherein the powder coating composition comprises one or more optionaladditives selected from lubricants, adhesion promoters, crosslinkers,catalysts, colorants (e.g., pigments or dyes), ferromagnetic particles,degassing agents, levelling agents, wetting agents, surfactants, flowcontrol agents, heat stabilizers, anti-corrosion agents, adhesionpromoters, inorganic fillers, metal driers, and combinations thereof.

Embodiment C-43 is the method of Embodiment C-42, wherein the powdercoating composition further comprises one or more lubricants, which isincorporated into the hardened coating.

Embodiment C-44 is the method of any of the previous embodiments,further comprising applying one or more lubricants to the hardenedcoating.

Embodiment C-45 is the method of Embodiment C-43 or C-44, wherein theone or more lubricants are present in or on the hardened coating in anamount of at least 0.1 wt-%, at least 0.5 wt-%, or at least 1 wt-%,based on the total weight of the hardened coating.

Embodiment C-46 is the method of any of Embodiments C-43 through C-45,wherein the one or more lubricants are present in or on the hardenedcoating in an amount of up to 4 wt-%, up to 3 wt-%, or up to 2 wt-%,based on the total weight of the hardened coating.

Embodiment C-47 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise agglomerates (i.e.,clusters) of primary polymer particles.

Embodiment C-48 is the method of any of the preceding embodiments,wherein the powder coating composition is substantially free of each ofbisphenol A, bisphenol F, and bisphenol S, structural units derivedtherefrom, or both.

Embodiment C-49 is the method of any of the preceding embodiments,wherein the powder coating composition is substantially free of allbisphenol compounds, structural units derived therefrom, or both, exceptfor TMBPF.

Embodiment C-50 is the method of any of the preceding embodiments,wherein the coating includes less than 50 ppm, less than 25 ppm, lessthan 10 ppm, or less than 1 ppm, extractables, if any, when testedpursuant to the Global Extraction Test.

Embodiment C-51 is the method of any of the preceding embodiments,wherein the adherent coating adheres to a substrate, such as a metalsubstrate, according to the Adhesion Test with an adhesion rating of 9or 10, preferably 10.

Embodiment C-52 is the method of any of the preceding embodiments,wherein the continuous hardened coating is free of pinholes and othercoating defects that result in exposed substrate. Such filmimperfections/failures can be indicated by a current flow measured inmilliamps (mA) using the Flat Panel Continuity Test described in theExamples Section.

Embodiment C-53 is the method of any of the preceding embodiments,wherein the powder coating composition which, when applied to a cleanedand pretreated aluminum panel and subjected to a curative bake for anappropriate duration to achieve a 242° C. peak metal temperature (PMT)and a dried film thickness of approximately 7.5 milligram per squareinch and formed into a fully converted 202 standard opening beverage canend, passes less than 5 milliamps of current while being exposed for 4seconds to an electrolyte solution containing 1% by weight of NaCldissolved in deionized water.

Embodiment C-54 is a coated metal substrate having a surface at leastpartially coated with a coating prepared by the method of any of thepreceding embodiments.

Embodiment C-55 is metal packaging (e.g., a metal packaging containersuch as a food, beverage, aerosol, or general packaging container (e.g.,can), a portion thereof, or a metal closure) comprising a metalsubstrate having a surface at least partially coated with a coatingprepared by the method of any of embodiments C-1 through C-53.

Embodiment C-56 is the metal packaging of embodiment C-55, wherein thesurface is an interior surface, an exterior surface, or both, of acontainer (e.g., can) body.

Embodiment C-57 is the metal packaging of embodiment C-55, wherein thesurface is a surface of a riveted can end and/or a pull tab.

Embodiment C-58 is the metal packaging of embodiments C-55 to C-57,which is filled with a food, beverage, or aerosol product.

Embodiments D: Coated Metal Substrate

Embodiment D-1 is a coated metal substrate comprising a metal substratehaving a hardened continuous adherent coating disposed on at least aportion of a surface thereof, wherein: the metal substrate has anaverage thickness of up to 635 microns; the hardened continuous adherentcoating has an average thickness of up to 100 microns (preferably up to50 microns, more preferably up to 25 microns, even more preferably up to20 microns, still more preferably up to 15 microns, and most preferablyup to 10 microns); the hardened continuous adherent coating is formedfrom a metal packaging can powder coating composition comprising powderpolymer particles (preferably, spray dried powder polymer particles)comprising a polymer having a number average molecular weight of atleast 2000 Daltons, wherein the powder polymer particles have a particlesize distribution having a D50 of less than 25 microns; and preferablythe hardened continuous adherent coating comprises less than 50 ppm,less than 25 ppm, less than 10 ppm, or less than 1 ppm, extractables, ifany, when tested pursuant to the Global Extraction Test.

Embodiment D-2 is the coated metal substrate of embodiment D-1, whereina lubricant is present in the powder polymer particles, on the powderpolymer particles, in another ingredient used to form the powder coatingcomposition, on a surface of the hardened coating, or a combinationthereof.

Embodiment D-3 is the coated metal substrate of Embodiment D-2, whereinthe lubricant is present in an amount of at least 0.1 wt-%, or at least0.5 wt-%, or at least 1 wt-%, based on the total weight of the powdercoating composition or hardened coating.

Embodiment D-4 is the coated metal substrate of Embodiments D-2 or D-3,wherein the lubricant is present in an amount of up to 4 wt-%, or up to3 wt-%, or up to 2 wt-%, based on the total weight of the powder coatingcomposition or hardened coating.

Embodiment D-5 is the coated metal substrate of any of the previousembodiments, wherein the powder coating composition comprises at least50 wt-%, at least 60 wt-%, at least 70 wt-%, at least 80 wt-%, or atleast 90 wt-% of the powder polymer particles, based on the total weightof the powder coating composition.

Embodiment D-6 is the coated metal substrate of any of the previousembodiments, wherein the powder coating composition comprises up to 100wt-%, up to 99.99 wt-%, up to 95 wt-%, or up to 90 wt-%, of the powderpolymer particles, based on the total weight of the powder coatingcomposition.

Embodiment D-7 is the coated metal substrate of any of the precedingembodiments, wherein the powder coating composition comprises one ormore charge control agents in contact with the powder polymer particles.

Embodiment D-8 is the coated metal substrate of Embodiment D-7, whereinthe powder coating composition comprises at least 0.01 wt-%, at least0.1 wt-%, or at least 1 wt-%, of the one or more charge control agents,based on the total weight of the powder coating composition.

Embodiment D-9 is the coated metal substrate of Embodiment D-7 or D-8,wherein the powder coating composition comprises up to 10 wt-%, up to 9wt-%, up to 8 wt-%, up to 7 wt-%, up to 6 wt-%, up to 5 wt-%, up to 4wt-%, or up to 3 wt-%, of the one or more charge control agents, basedon the total weight of the powder coating composition.

Embodiment D-10 is the coated metal substrate of any of the precedingembodiments, wherein the metal substrate comprises steel, stainlesssteel, tin-free steel (TFS), tin-plated steel, electrolytic tin plate(ETP), or aluminum.

Embodiment D-11 is the coated metal substrate of any of the precedingembodiments, wherein the metal substrate has an average thickness of upto 375 microns.

Embodiment D-12 is the coated metal substrate of any of the precedingembodiments, wherein the metal substrate has an average thickness of atleast 125 microns.

Embodiment D-13 is the coated metal substrate of any of the precedingembodiments, wherein the hardened adherent coating has an averagethickness of up to 25 microns, up to 20 microns, up to 15 microns, or upto 10 microns.

Embodiment D-14 is the coated metal substrate of any of the precedingembodiments, wherein the hardened adherent coating has an averagethickness of at least 1 micron, at least 2 microns, at least 3 microns,or at least 4 microns.

Embodiment D-15 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles have a particle sizedistribution having a D50 of less than 20 microns, less than 15 microns,or less than 10 microns.

Embodiment D-16 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles have a particle sizedistribution having a D90 of less than 25 microns, less than 20 microns,less than 15 microns, or less than 10 microns.

Embodiment D-17 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles are chemicallyproduced (as opposed to mechanically produced (e.g., ground) polymerparticles).

Embodiment D-18 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles have a shape factor of100-140 (spherical and potato shaped) (or 120-140 (e.g., potatoshaped)).

Embodiment D-19 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles have a compressibilityindex of 1 to 20 (or 1 to 10, 11 to 15, or 16 to 20).

Embodiment D-20 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles have a Haussner Ratioof 1.00 to 1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25).

Embodiment D-21 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles comprise athermoplastic polymer.

Embodiment D-22 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles comprise a polymerhaving a melt flow index greater than 15 grams/10 minutes, greater than50 grams/10 minutes, or greater than 100 grams/10 minutes, and incertain embodiments, a melt flow index of up to 200 grams/10 minutes, orup to 150 grams/10 minutes.

Embodiment D-23 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles comprise an amorphouspolymer having a glass transition temperature (Tg) of at least 0° C., atleast 30° C., at least 40° C., at least 50° C., at least 60° C., or atleast 70° C.

Embodiment D-24 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles comprise an amorphouspolymer having a Tg of up to 150° C., up to 125° C., up to 110° C., upto 100° C., or up to 80° C.

Embodiment D-25 is the coated metal substrate of any of the precedingembodiments, wherein the hardened coating does not have any detectableTg.

Embodiment D-26 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles comprise a crystallineor semi-crystalline polymer having a melting point of at least 40° C.and up to 130° C.

Embodiment D-27 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles comprise a polymerselected from a polyacrylic, polyether, polyolefin, polyester,polyurethane, polycarbonate, polystyrene, or a combination thereof(i.e., copolymer or mixture thereof such as acrylonitrile butadienestyrene). Preferably, the polymer is selected from a polyacrylic,polyether, polyolefin, polyester, or a combination thereof.

Embodiment D-28 is the coated metal substrate of any of the precedingembodiments, wherein the polymer Mn is at least 5,000 Daltons, at least10,000 Daltons, or at least 15,000 Daltons.

Embodiment D-29 is the coated metal substrate of any of the precedingembodiments, wherein the polymer Mn is up to 10,000,000 Daltons, up to1,000,000 Daltons, up to 100,000 Daltons, or up to 20,00 Daltons.

Embodiment D-30 is the coated metal substrate of any of the precedingembodiments, wherein the polymer has a polydispersity index (Mw/Mn) ofless than 4, less than 3, less than 2, or less than 1.5.

Embodiment D-31 is the coated metal substrate of any of Embodiments D-7through D-30, wherein the one or more charge control agents enable thepowder polymer particles to efficiently accept a triboelectric charge tofacilitate application to a substrate.

Embodiment D-32 is the coated metal substrate of any of Embodiments D-7through D-31, wherein the one or more charge control agents compriseparticles having particle sizes in the sub-micron range (e.g., less than1 micron, 100 nanometers or less, 50 nanometers or less, or 20nanometers or less).

Embodiment D-33 is the coated metal substrate of any of Embodiments D-7through D-32, wherein the one or more charge control agents compriseinorganic particles.

Embodiment D-34 is the coated metal substrate of any of Embodiments D-7through D-33, wherein the one or more charge control agents comprisehydrophilic fumed aluminum oxide particles, hydrophilic precipitatedsodium aluminum silicate particles, metal carboxylate and sulfonateparticles, quaternary ammonium salts (e.g., quaternary ammonium sulfateor sulfonate particles), polymers containing pendant quaternary ammoniumsalts, ferromagnetic particles, transition metal particles, nitrosine orazine dyes, copper phthalocyanine pigments, metal complexes of chromium,zinc, aluminum, zirconium, calcium, or combinations thereof.

Embodiment D-35 is the coated metal substrate of any of the precedingembodiments, wherein the powder coating composition comprises one ormore optional additives selected from adhesion promoters, crosslinkers,catalysts, colorants (e.g., pigments or dyes), ferromagnetic particles,degassing agents, levelling agents, wetting agents, surfactants, flowcontrol agents, heat stabilizers, anti-corrosion agents, adhesionpromoters, inorganic fillers, metal driers, and combinations thereof.

Embodiment D-36 is the coated metal substrate of any of the precedingembodiments, wherein the powder polymer particles comprise agglomerates(i.e., clusters) of primary polymer particles.

Embodiment D-37 is the coated metal substrate of Embodiment D-36,wherein the agglomerates have a particle size of 1 micron to 25 microns.

Embodiment D-38 is the coated metal substrate of Embodiment D-36 orD-37, wherein the primary polymer particles have a primary particle sizeof 0.05 micron to 8 microns.

Embodiment D-39 is the coated metal substrate of any of the precedingembodiments, wherein the powder coating composition is substantiallyfree of each of bisphenol A, bisphenol F, and bisphenol S, structuralunits derived therefrom, or both.

Embodiment D-40 is the coated metal substrate of any of the precedingembodiments, wherein the powder coating composition is substantiallyfree of all bisphenol compounds, structural units derived therefrom, orboth, except for TMBPF.

Embodiment D-41 is the coated metal substrate of any of the precedingembodiments, wherein the adherent coating adheres to the metal substrateaccording to the Adhesion Test with an adhesion rating of 9 or 10,preferably 10.

Embodiment D-42 is the coated metal substrate of any of the precedingembodiments, wherein the continuous hardened coating is free of pinholesand other coating defects that result in exposed substrate. Such filmimperfections/failures can be indicated by a current flow measured inmilliamps (mA) using the Flat Panel Continuity Test described in theExamples Section.

Embodiment D-43 is the coated metal substrate of any of the precedingembodiments, wherein the powder coating composition which, when appliedto a cleaned and pretreated aluminum panel and subjected to a curativebake for an appropriate duration to achieve a 242° C. peak metaltemperature (PMT) and a dried film thickness of approximately 7.5milligram per square inch and formed into a fully converted 202 standardopening beverage can end, passes less than 5 milliamps of current whilebeing exposed for 4 seconds to an electrolyte solution containing 1% byweight of NaCl dissolved in deionized water.

Embodiment D-44 is the coated metal substrate of any of the precedingembodiment, wherein the metal substrate comprises a pre-treated orprimed substrate.

Embodiment D-45 is metal packaging (e.g., a metal packaging container, aportion thereof, or a metal closure) comprising a coated metal substrateof any of the preceding embodiments.

Embodiment D-46 is the metal packaging of Embodiment 45, wherein thecoated surface of the metal substrate forms an interior surface of a canbody.

Embodiment D-47 is the metal packaging of Embodiment D-45 or D-46,wherein the coated surface of the metal substrate forms an exteriorsurface of a can body.

Embodiment D-48 is the metal packaging of Embodiment 45, wherein thecoated surface is a surface of a riveted can end and/or a pull tab.

Embodiment D-49 is the metal packaging of Embodiments D-45 through D-48,wherein the can is filled with a food, beverage, or aerosol product.

Embodiments E: Method of Making Metal Packaging

Embodiment E-1 is a method of making metal packaging (e.g., a metalpackaging container such as a food, beverage, aerosol, or generalpackaging container (e.g., can), a portion thereof, or a metal closuresuch as for a metal packaging container or a glass jar), the methodcomprising: providing a metal substrate having a hardened continuousadherent coating disposed on at least a portion of a surface thereof,wherein: the metal substrate has an average thickness of up to 635microns; the hardened continuous adherent coating is formed from a metalpackaging powder coating composition; wherein the powder coatingcomposition comprises powder polymer particles (preferably, spray driedpowder polymer particles) comprising a polymer having a number averagemolecular weight of at least 2000 Daltons, wherein the powder polymerparticles have a particle size distribution having a D50 of less than 25microns; and forming the substrate into at least a portion of a metalpackaging container (e.g., a food, beverage, aerosol, or generalpackaging container (e.g., can)), a portion thereof, or a metal closure(e.g., for a metal packaging container or a glass jar).

Embodiment E-2 is the method of embodiment E-1, wherein a lubricant ispresent in the powder polymer particles, on the powder polymerparticles, in another ingredient used to form the powder coatingcomposition, on a surface of the hardened coating, or a combinationthereof.

Embodiment E-3 is the method of Embodiment E-2, wherein the lubricant ispresent in an amount of at least 0.1 wt-%, or at least 0.5 wt-%, or atleast 1 wt-%, based on the total weight of the powder coatingcomposition or hardened coating.

Embodiment E-4 is the method of Embodiments E-2 or E-3, wherein thelubricant is present in an amount of up to 4 wt-%, or up to 3 wt-%, orup to 2 wt-%, based on the total weight of the powder coatingcomposition or hardened coating.

Embodiment E-5 is the method of any of the previous embodiments, whereinthe powder coating composition comprises at least 50 wt-%, at least 60wt-%, at least 70 wt-%, at least 80 wt-%, or at least 90 wt-% of thepowder polymer particles, based on the total weight of the powdercoating composition.

Embodiment E-6 is the method of any of the previous embodiments, whereinthe powder coating composition comprises up to 100 wt-%, up to 99.99wt-%, up to 95 wt-%, or up to 90 wt-%, of the powder polymer particles,based on the total weight of the powder coating composition.

Embodiment E-7 is the method of any of the preceding embodiments,wherein the powder coating composition comprises one or more chargecontrol agents in contact with the powder polymer particles.

Embodiment E-8 is the method of Embodiment E-7, wherein the powdercoating composition comprises at least 0.01 wt-%, at least 0.1 wt-%, orat least 1 wt-%, of the one or more charge control agents, based on thetotal weight of the powder coating composition.

Embodiment E-9 is the method of Embodiment E-7 or E-8, wherein thepowder coating composition comprises up to 10 wt-%, up to 9 wt-%, up to8 wt-%, up to 7 wt-%, up to 6 wt-%, up to 5 wt-%, up to 4 wt-%, or up to3 wt-%, of the one or more charge control agents, based on the totalweight of the powder coating composition.

Embodiment E-10 is the method of any of the preceding embodiments,wherein the metal substrate comprises steel, stainless steel, tin-freesteel (TFS), tin-plated steel, electrolytic tin plate (ETP), oraluminum.

Embodiment E-11 is the method of any of the preceding embodiments,wherein the metal substrate has an average thickness of up to 375microns.

Embodiment E-12 is the method of any of the preceding embodiments,wherein the metal substrate has an average thickness of at least 125microns.

Embodiment E-13 is the method of any of the preceding embodiments,wherein the hardened adherent coating has an average thickness of up to100 microns (preferably up to 50 microns, more preferably up to 25microns, even more preferably up to 20 microns, still more preferably upto 15 microns, and most preferably up to 10 microns).

Embodiment E-14 is the method of any of the preceding embodiments,wherein the hardened adherent coating has an average thickness of atleast 1 micron, at least 2 microns, at least 3 microns, or at least 4microns.

Embodiment E-15 is the method of any of the preceding embodiments,wherein the powder polymer particles have a particle size distributionhaving a D50 of less than 20 microns, less than 15 microns, or less than10 microns.

Embodiment E-16 is the method of any of the preceding embodiments,wherein the powder polymer particles have a particle size distributionhaving a D90 of less than 25 microns, less than 20 microns, less than 15microns, or less than 10 microns.

Embodiment E-17 is the method of any of the preceding embodiments,wherein the powder polymer particles are chemically produced (as opposedto mechanically produced (e.g., ground) polymer particles).

Embodiment E-18 is the method of any of the preceding embodiments,wherein the powder polymer particles have a shape factor of 100-140(spherical and potato shaped) (or 120-140 (e.g., potato shaped)).

Embodiment E-19 is the method of any of the preceding embodiments,wherein the powder polymer particles have a compressibility index of 1to 20 (or 1 to 10, 11 to 15, or 16 to 20).

Embodiment E-20 is the method of any of the preceding embodiments,wherein the powder polymer particles have a Haussner Ratio of 1.00 to1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25).

Embodiment E-21 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a thermoplastic polymer.

Embodiment E-22 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a polymer having a meltflow index greater than 15 grams/10 minutes, greater than 50 grams/10minutes, or greater than 100 grams/10 minutes, and in certainembodiments, a melt flow index of up to 200 grams/10 minutes, or up to150 grams/10 minutes.

Embodiment E-23 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise an amorphous polymerhaving a glass transition temperature (Tg) of at least 0° C., at least30° C., at least 40° C., at least 50° C., at least 60° C., or at least70° C.

Embodiment E-24 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise an amorphous polymerhaving a Tg of up to 150° C., up to 125° C., up to 110° C., up to 100°C., or up to 80° C.

Embodiment E-25 is the method of any of the preceding embodiments,wherein the hardened coating does not have any detectable Tg.

Embodiment E-26 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a crystalline orsemi-crystalline polymer having a melting point of at least 40° C. andup to 130° C.

Embodiment E-27 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise a polymer selected from anacrylic (i.e., acrylate), polyether, polyolefin, polyester,polyurethane, polyurethane, polycarbonate, polystyrene, or a combinationthereof (i.e., copolymer or mixture thereof such as acrylonitrilebutadiene styrene).

Embodiment E-28 is the method of any of the preceding embodiments,wherein the polymer Mn is at least 5,000 Daltons, at least 10,000Daltons, or at least 15,000 Daltons.

Embodiment E-29 is the method of any of the preceding embodiments,wherein the polymer Mn is up to 10,000,000 Daltons, up to 1,000,000Daltons, up to 100,000 Daltons, or up to 20,00 Daltons.

Embodiment E-30 is the method of any of the preceding embodiments,wherein the polymer has a polydispersity index (Mw/Mn) of less than 4,less than 3, less than 2, or less than 1.5.

Embodiment E-31 is the method of any of Embodiments E-7 through E-30,wherein the one or more charge control agents enable the powder polymerparticles to efficiently accept a triboelectric charge to facilitateapplication to a substrate.

Embodiment E-32 is the method of any of Embodiments E-7 through E-31,wherein the one or more charge control agents comprise particles havingparticle sizes in the sub-micron range (e.g., less than 1 micron, 100nanometers or less, 50 nanometers or less, or 20 nanometers or less).

Embodiment E-33 is the method of any of Embodiments E-7 through E-32,wherein the one or more charge control agents comprise inorganicparticles.

Embodiment E-34 is the method of any of Embodiment E-7 through E-33,wherein the one or more charge control agents comprise hydrophilic fumedaluminum oxide particles, hydrophilic precipitated sodium aluminumsilicate particles, metal carboxylate and sulfonate particles,quaternary ammonium salts (e.g., quaternary ammonium sulfate orsulfonate particles), polymers containing pendant quaternary ammoniumsalts, ferromagnetic particles, transition metal particles, nitrosine orazine dyes, copper phthalocyanine pigments, metal complexes of chromium,zinc, aluminum, zirconium, calcium, or combinations thereof.

Embodiment E-35 is the method of any of the preceding embodiments,wherein the powder coating composition comprises one or more optionaladditives selected from adhesion promoters, crosslinkers, catalysts,colorants (e.g., pigments or dyes), ferromagnetic particles, degassingagents, levelling agents, wetting agents, surfactants, flow controlagents, heat stabilizers, anti-corrosion agents, adhesion promoters,inorganic fillers, and combinations thereof.

Embodiment E-36 is the method of any of the preceding embodiments,wherein the powder polymer particles comprise agglomerates (i.e.,clusters) of primary polymer particles.

Embodiment E-37 is the method of Embodiment E-36, wherein theagglomerates have a particle size of 1 micron to 25 microns.

Embodiment E-38 is the method of Embodiment E-36 or E-37, wherein theprimary polymer particles have a primary particle size of 0.05 micron to8 microns.

Embodiment E-39 is the method of any of the preceding embodiments,wherein the powder coating composition is substantially free ofbisphenol A, bisphenol F, and bisphenol S, structural units derivedtherefrom, or both.

Embodiment E-40 is the method of any of the preceding embodiments,wherein the powder coating composition is substantially free of allbisphenol compounds, structural units derived therefrom, or both, exceptfor TMBPF.

Embodiment E-41 is the method of any of the preceding embodimentswherein the hardened continuous adherent coating comprises less than 50ppm, less than 25 ppm, less than 10 ppm, or less than 1 ppm,extractables, if any, when tested pursuant to the Global ExtractionTest.

Embodiment E-42 is the method of any of the preceding embodiments,wherein the adherent coating adheres to the metal substrate according tothe Adhesion Test with an adhesion rating of 9 or 10, preferably 10.

Embodiment E-43 is the method of any of the preceding embodiments,wherein the continuous hardened coating is free of pinholes and othercoating defects that result in exposed substrate. Such filmimperfections/failures can be indicated by a current flow measured inmilliamps (mA) using the Flat Panel Continuity Test described in theExamples Section.

Embodiment E-44 is the method of any of the preceding embodiments,wherein the powder coating composition which, when applied to a cleanedand pretreated aluminum panel and subjected to a curative bake for anappropriate duration to achieve a 242° C. peak metal temperature (PMT)and a dried film thickness of approximately 7.5 milligram per squareinch and formed into a fully converted 202 standard opening beverage canend, passes less than 5 milliamps of current while being exposed for 4seconds to an electrolyte solution containing 1% by weight of NaCldissolved in deionized water.

EXAMPLES

These Examples are merely for illustrative purposes and are not meant tobe overly limiting on the scope of the appended embodiments.Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the present disclosure are approximations, thenumerical values set forth in the specific examples are reported asprecisely as possible. Any numerical value, however, inherently containscertain errors necessarily resulting from the standard deviation foundin their respective testing measurements. At the very least, and not asan attempt to limit the application of the doctrine of equivalents tothe scope of the embodiments, each numerical parameter should at leastbe construed in light of the number of reported significant digits andby applying ordinary rounding techniques.

Unless otherwise noted, all parts, percentages, ratios, etc. in theexamples and the rest of the specification are by weight, and allreagents used in the examples were obtained, or are available, fromgeneral chemical suppliers such as, for example, Sigma-Aldrich Company,Saint Louis, Missouri, or may be synthesized by conventional methods.The following abbreviations may be used in the following examples:ppm=parts per million; phr=parts per hundred rubber; mL=milliliter;L=liter; m=meter, mm=millimeter, cm=centimeter, kg=kilogram, g=gram,min=minute, s=second, hrs=hour, ° C.=degrees Celsius, ° F.=degreesFarenheit, MPa=megapascals, and N-m=Newton-meter, Mn=number averagemolecular weight, cP=centipoise.

Test Methods

Unless indicated otherwise, the following test methods may be utilized.

Adhesion Test

Adhesion testing was performed according to ASTM D 3359-17 (2017), TestMethod B, for coatings ≤125 microns thick, using SCOTCH 610 tape(available from 3M Company of Saint Paul, MN) and a lattice patternconsisting of 4 scratches across and 4 scratches down (roughly 1-2 mmapart). The test is typically repeated 3 times per sample. Adhesion israted on a scale of 0-10 where a rating of “10” indicates no adhesionfailure, a rating of “9” indicates 90% of the coating remains adhered, arating of “8” indicates 80% of the coating remains adhered, and so on.Adhesion ratings of 9 or 10 are typically desired for commerciallyviable coatings. Thus, herein, an adhesion rating of 9 or 10, preferably10, is considered to be adherent.

Differential Scanning calorimetry for Tg

Samples of powder composition for differential scanning calorimetry(“DSC”) testing are weighed into standard sample pans, and analyzedusing the standard DSC heat-cool-heat method. The samples areequilibrated at −60° C., then heated at 20° C. per minute to 200° C.,cooled to −60° C., and then heated again at 20° C. per minute to 200° C.Glass transition temperatures are calculated from the thermogram of thelast heat cycle. The glass transition is measured at the inflectionpoint of the transition.

Molecular Weight Determination by Gel Permeation Chromatography

Samples for Gel Permeation Chromatography (“GPC”) testing are preparedby first dissolving the powder polymer in a suitable solvent (e.g., THFif appropriate for a given powder polymer). An aliquot of this solutionis then analyzed by GPC along with mixtures of polystyrene (“PS”)standards. The molecular weights of the samples are calculated afterprocessing the GPC runs and verifying the standards.

Global Extraction Test

The global extraction test is designed to estimate the total amount ofmobile material that can potentially migrate out of a coating and intofood packed in a coated can. Typically, a coated substrate is subjectedto water or solvent blends under a variety of conditions to simulate agiven end-use.

Acceptable extraction conditions and media can be found in 21 CFR §175.300, paragraphs (d) and (e). The extraction procedure used in thecurrent invention was conducted in accordance with the Food and DrugAdministration (FDA) “Preparation of Premarket Submission for FoodContact Substances: Chemistry Recommendations,” (December 2007). Theallowable global extraction limit as defined by the FDA regulation is 50parts per million (ppm).

The single-sided extraction cells are made according to the design foundin the Journal of the Association of Official Agricultural Chemists,47(2):387(1964), with minor modifications. The cell is 9 in (inches)×9in×0.5 in with a 6 in×6 in open area in the center of the TEFLON spacer.This allows for 36 in² or 72 in² of test article to be exposed to thefood simulating solvent. The cell holds 300 mL of food simulatingsolvent. The ratio of solvent to surface area is then 8.33 mL/in² and4.16 mL/in² when 36 in² and 72 in² respectively of test article areexposed.

For the purpose of this invention, the test articles consist of0.0082-inch-thick 5182 aluminum alloy panels, pretreated withPermatreat® 1903 (supplied by Chemetall GmbH, Frankfurt am Main,Germany). These panels are coated with the test coating (completelycovering at least the 6 in×6 in area required to fit the test cell) toyield a final, dry film thickness of 11 grams per square meter (gsm)following a 10 second curative bake resulting in a 242° C. peak metaltemperature (PMT). Two test articles are used per cell for a totalsurface area of 72 in² per cell. The test articles are extracted inquadruplicate using 10% aqueous ethanol as the food-simulating solvent.The test articles are processed at 121° C. for two hours, and thenstored at 40° C. for 238 hours. The test solutions are sampled after 2,24, 96 and 240 hours. The test article is extracted in quadruplicateusing the 10% aqueous ethanol under the conditions listed above.

Each test solution is evaporated to dryness in a preweighed 50 mL beakerby heating on a hot plate. Each beaker is dried in a 250° F. (121° C.)oven for a minimum of 30 minutes. The beakers are then placed into adesiccator to cool and then weighed to a constant weight. Constantweight is defined as three successive weighings that differ by no morethan 0.00005 g.

Solvent blanks using Teflon sheet in extraction cells are similarlyexposed to simulant and evaporated to constant weight to correct thetest article extractive residue weights for extractive residue added bythe solvent itself. Two solvent blanks are extracted at each time pointand the average weight is used for correction.

Total nonvolatile extractives are calculated as follows:

$E_{x} = \frac{e}{s}$where: Ex=Extractive residues (mg/in²)

-   -   e=Extractives per replicate tested (mg)    -   s Area extracted (in²)

Preferred coatings give global extraction results of less than 50 ppm,less than 25 ppm, than 10 ppm, or less than 1 ppm. Most preferably, theglobal extraction results are optimally non-detectable.

Flat Panel Continuity Test

This test measures the continuity of a coating applied to a flat metalsubstrate and indicates the presence or absence of a continuous film,largely free of pores, cracks, or other defects that could expose themetal substrate. This method may be used for both laboratory andcommercially coated steel and aluminum substrates. A test assembly isemployed that consists of: a non-conducting, solid base (large enough tosupport the test panel); a hinged clamping mechanism that is mounted tothe base; a non-conductive electrolyte holding cell, connected to theclamping mechanism in such a way that it can be lowered and sealed ontothe test panel (resulting in a 6 inch-diameter, circular area on thetest panel being exposed to the electrolyte); a hole in the electrolyteholding cell large enough to fill the cell with electrolyte; and anelectrode inserted into the electrolyte holding cell. A WACO EnamelRater II (available from the Wilkens-Anderson Company, Chicago, IL),with an output voltage of 6.3 volts is used in conjunction with the testassembly (as described below) to measure metal exposure in the form ofelectrical current. The electrolyte solution used in the following testconsists of 1%-by-weight Sodium Chloride dissolved in deionized water.

An 8-inch by 8-inch panel of metal is coated and cured with the coatingto be tested, as prescribed by the formula or technical data sheet. Ifno coating thickness or cure schedule is prescribed for the testcoating, test panels should be coated in such a way to yield a final,dry film thickness of 11 grams per square meter (gsm) utilizing acurative bake with an appropriate duration to achieve a 242° C. peakmetal temperature (PMT). Each test panel may only be used once andshould be visibly free of scratches or abrasions. The test panel isplaced in the test assembly with the test coating facing up. Theelectrolyte holding cell is then lowered onto the test panel and lockedin place by closing the clamp. The positive lead wire from the enamelrater is connected to the edge of the panel in an area free of coating.A small area may need to be sanded or scraped to expose the bare metalsubstrate. The electrolyte cell is then filled with enough electrolytesolution to ensure contact with the cell's negative post. The negativelead wire from the enamel rater is connected to the negative post on topof the cell. Finally, the probe on the Waco enamel rater is lowered toactivate the test current.

Film imperfections/failure will be indicated by a current flow measuredin milliamps (mA). The initial milliamp reading is recorded for eachpanel tested, and results are reported in milliamps. If more than onedetermination per variable is run, the average reading is reported.Preferred coatings of the present invention pass less than 10 mA whentested as described above, more preferably less than 5 mA, mostpreferably less than 2 mA, and optimally less than 1 mA.

Flexibility Test

This test measures the ability of a coated substrate to retain itsintegrity as it undergoes the formation process necessary to produce afabricated article such as a riveted beverage can end. It is a measureof the presence or absence of cracks or fractures in the formed end. Theend is typically placed on a cup filled with an electrolyte solution.The cup is inverted to expose the surface of the end to the electrolytesolution. The intensity of the current that passes through the end isthen measured. If the coating remains intact (no cracks or fractures)after fabrication, minimal current will pass through the end.

For the present evaluation, fully converted 202 standard openingbeverage ends were exposed for a period of 4 seconds to aroom-temperature electrolyte solution comprised of 1% NaCl by weight indeionized water. The coating to be evaluated was present on the interiorsurface of the beverage end at a dry film thickness of 6 to 7.5milligrams per square inch (“msi”) (or 9.3 to 11.6 grams per squaremeter), with 7 msi being the target thickness and having been cured asprescribed by the formula or technical data sheet. If no cure scheduleis prescribed for the test coating, test panels should be coatedutilizing a curative bake with an appropriate duration to achieve a 242°C. peak metal temperature (PMT). Metal exposure was measured using aWACO Enamel Rater II (available from the Wilkens-Anderson Company,Chicago, IL) with an output voltage of 6.3 volts. The measuredelectrical current intensity, in milliamps, is reported. Endcontinuities are typically tested initially and then after the ends aresubjected to pasteurization, Dowfax, or retort.

Preferred coatings of the present invention initially pass less than 10milliamps (mA) when tested as described above, more preferably less than5 mA, most preferably less than 2 mA, and optimally less than 1 mA.After pasteurization, Dowfax detergent test, or retort, preferredcoatings give continuities of less than 20 mA, more preferably less than10 mA, even more preferably less than 5 mA, and even more preferablyless than 1 mA.

Preparation of Polyester Polymer Particles

The general procedure employed for polyester particles is described inExamples 1 or 3 of U.S. Pat. No. 9,920,217 (Skillman et al.). Dry powderhaving a suitable particle size distribution, shape factor, and the likeis achieved, for example, via spray drying.

Preparation of Acrylic Polymer Particles

Preparation of Acid-Functional Acrylic Pre-Polymer A:

A premix of 2245.54 parts glacial methacrylic acid, 1496.93 partsstyrene, 1247.41 parts ethyl acrylate (EA), 2345.70 parts n-butanol,167.58 parts deionized water, and 299.34 parts t-butyl peroctoate areprepared in a premix vessel. To a 5-liter reaction vessel equipped witha stirrer, reflux condenser, thermocouple, heating and coolingcapability, and inert gas blanket, 1778.65 parts n-butanol and 85.25parts deionized water are added. With agitation and an inert gas blanketon, the reaction vessel is heated to 97° C. Once within the temperaturerange, 46.44 parts t-butyl peroctoate is added. Five minutes after thet-butyl peroctoate addition, the premix is added at a constant rate tothe reaction vessel over two and a half hours maintaining thetemperature range of 97° C. to 102° C. After the premix addition iscomplete, the premix vessel is rinsed with 118.63 parts n-butanol goinginto the reaction vessel. Immediately after rinsing, a second premix of59.33 parts t-butyl peroctoate and 24.00 parts n-butanol is added to thereaction vessel over 60 minutes maintaining the temperature range. Atthe end of the addition, the premix vessel is rinsed into the reactionvessel with 22.00 parts n-butanol. Thirty minutes after rinsing thesecond premix vessel, 12.89 parts t-butyl peroctoate and 1.00 partsn-butanol are added to the reaction vessel. The reaction is allowed toproceed for an additional 2 hours at temperature. Following the hold,47.32 parts deionized water is added and the reaction vessel cooled toless than 60° C. This process produces an acid functional acrylicpre-polymer with solids of approximately 50.0% nonvolatile mass (NVM),an acid number of approximately 290, and a Brookfield viscosity ofapproximately 25,000 centipoise at 80° F. (26.7° C.).

Preparation of Emulsion Polymer Using Acid-Functional AcrylicPre-Polymer A as the Surfactant:

To a 5-liter reaction vessel equipped with a stirrer, reflux condenser,thermocouple, heating and cooling capability, and inert gas blanket,326.7 parts A and 950.92 parts deionized water is added. With theagitation activated, the inert gas blanket on and system is set topartial reflux. To the vessel 39.3 parts 29% aqueous ammonium hydroxideis added. The temperature is set to 100° C. and the n-butanol isdistilled under atmospheric pressure. Once n-butanol distillationsubsided, the vessel is cooled to 50° C. and 314.85 part of deionizedwater is added to the vessel and heat is reengaged and set to 70° C. Inthe meantime a monomer premix of 214.76 parts styrene and 252.11 partsbutyl acrylate (BA) is prepared. To the vessel 4.61 parts benzoin and7.40 parts deionized water are added and temperature was set to 81° C.At temperature, 4.89 parts 35% hydrogen peroxide solution and 2.80 partsdeionized water are added to the reaction vessel. The monomer premix isadded exactly 5 minutes after hydrogen peroxide addition at a constantrate over 30 minutes. Following the monomer premix addition, 16.52 partsdeionized water is added and the reaction is allowed to proceed for 10minutes. Following the brief hold, 0.80 parts benzoin, 0.83 parts 35%hydrogen peroxide solution, and 5.55 parts deionized water are added tothe reaction vessel. The reaction is allowed to proceed for another 45minutes. At the end of this hold, 0.26 parts benzoin, 0.28 part 35%hydrogen peroxide solution, and 5.58 parts deionized water are added.The reaction once again is allowed to stir for 2 hours at temperature.The heat is disengaged at the end of the hold and 2.52 parts TRIGONOXA-W70, 0.35 parts iron complex solution, 1.74 parts erythorbic acid,1.87 parts 29% aqueous ammonium hydroxide, and 17.74 parts deionizedwater is added to the vessel. The reaction is allowed to exotherm andcool to room temperature. This process produces an acrylic emulsion withsolids of 31.3% NVM, and normal average particle size of 2.4 microns.

Preparation of Coating Composition Using Acrylic Emulsion Polymer

The acrylic emulsion is dried to form dry acrylic powder polymerparticles by spray drying, for example, using a B-290 mini-spray drierfrom Buchi, which may optionally be further modified to preventagglomeration. A hydrophobic silica charge control agent is added in anamount of 2-3 wt-%, based on the total weight of charge control agentand powder polymer particles. Aluminum oxide and aluminum hydroxide flowmodifiers are added to enhance fluidity. The acrylic powder particles inthe mixture are charged by friction between the particles and thesurface of a doctor blade. The charge distribution may be assessed byusing a charge spectrometer such as that available under the trade nameESPART by Hosokawa Micron Powder Systems (Osaka, Japan).

The coating composition is filled in a magnetic brush unit mounted at adistance of 2.5 millimeters (mm) from a rotating metal drum available asthe 1 d-tester (developer life time tester) from Epping GmbH. On therotating drum an aluminum sheet of 0.1 mm thickness is mounted. Therotation speed of the drum (i.e., coating speed) is 100 mm/minute, thespeed of the magnetic brush is 130 meter/minute in the same direction asthe drum. The doctor blade of the magnetic brush is adjusted to adistance of 1.5 mm to the magnetic roller. The magnetic pole is adjusted−10 degrees compared to the line between both rotating axes. Thedevelopment potential of the drum against the developer roller is set to1000V. The coated aluminum sheet, obtained after one development step,is then cured in an oven at 200° C. to obtain a homogeneous powdercoating with an average coating thickness of 25 microns and a toleranceof less than ±10%.

The complete disclosures of the patents, patent documents, andpublications cited herein are incorporated by reference in theirentirety as if each were individually incorporated. To the extent thatthere is any conflict or discrepancy between this specification aswritten and the disclosure in any document that is incorporated byreference herein, this specification as written will control. Variousmodifications and alterations to this disclosure will become apparent tothose skilled in the art without departing from the scope and spirit ofthis disclosure. It should be understood that this disclosure is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the disclosureintended to be limited only by the embodiments set forth herein asfollows.

What is claimed is:
 1. A method comprising: providing a metal packagingpowder coating composition, wherein the powder coating compositioncomprises chemically produced powder polymer particles and magneticcarrier particles; wherein the powder polymer particles comprise apolymer having a number average molecular weight of at least 2000Daltons, and wherein the powder polymer particles have a particle sizedistribution having a D50 of less than 20 microns; directing the powdercoating composition to at least a portion of a metal substrate, whereinthe metal substrate is a metal substrate for forming metal packaging andhas an average thickness of up to 635 microns; and providing conditionseffective for the powder coating composition to form a hardenedcontinuous adherent coating on at least a portion of the metalsubstrate, wherein the hardened continuous adherent coating has anaverage thickness of up to 100 microns.
 2. The method of claim 1,wherein the magnetic carrier particles are not transferred to the metalsubstrate.
 3. The method of claim 1, wherein the magnetic carrierparticles have a core comprising iron, steel, nickel, magnetite,γ-Fe₂O₃, or ferrites.
 4. The method of claim 1, wherein the powdercoating composition further comprises non-magnetic carrier particles. 5.The method of claim 1, wherein the chemically produced powder polymerparticles comprise agglomerates of primary polymer particles.
 6. Themethod of claim 1, wherein the powder coating composition furthercomprises one or more charge control agents in contact with thechemically produced powder polymer particles.
 7. The method of claim 1,wherein the powder coating composition further comprises one or morelubricants, or the method further comprises applying one or morelubricants to the hardened coating.
 8. The method of claim 1, whereindirecting the powder coating composition to at least a portion of themetal substrate comprises: feeding the powder coating composition to atransporter; and directing the powder coating composition from thetransporter to at least a portion of the metal substrate, by means of anelectromagnetic field.
 9. The method of claim 1, wherein the chemicallyproduced powder polymer particles are spray dried powder polymerparticles.
 10. The method of claim 1, wherein the chemically producedpowder polymer particles comprise a polymer selected from a polyacrylic,polyether, polyolefin, polyester, polyurethane, polycarbonate,polystyrene, or a combination thereof.
 11. The method of claim 1,further comprising forming the substrate having the hardened continuousadherent coating thereon into at least a portion of a metal packagingcontainer, a portion thereof, or a metal closure.
 12. A methodcomprising: providing a metal packaging powder coating composition,wherein the powder coating composition comprises chemically producedpowder polymer particles and magnetic carrier particles; wherein thepowder polymer particles comprise a polymer having a number averagemolecular weight of at least 2000 Daltons, wherein the powder polymerparticles have a particle size distribution having a D50 of less than 20microns; directing the powder coating composition to at least a portionof a metal substrate, wherein the magnetic carrier particles are nottransferred to the metal substrate, and wherein the metal substrate is ametal substrate for forming a food, beverage, or aerosol container, aportion thereof, or a metal closure, and has an average thickness of upto 635 microns; and providing conditions effective for the powdercoating composition to form a hardened continuous adherent coating on atleast a portion of the metal substrate, wherein the hardened continuousadherent coating has an average thickness of up to 100 microns.
 13. Themethod of claim 12, wherein the chemically produced powder polymerparticles are spray dried powder polymer particles.
 14. The method ofclaim 12, wherein the magnetic carrier particles have a core comprisingiron, steel, nickel, magnetite, γ-Fe₂O₃, or ferrites.
 15. The method ofclaim 12, wherein the powder coating composition further comprises oneor more charge control agents in contact with the chemically producedpowder polymer particles.
 16. The method of claim 12, wherein the powdercoating composition further comprises one or more lubricants, or themethod further comprises applying one or more lubricants to the hardenedcoating.
 17. The method of claim 12, wherein directing the powdercoating composition to at least a portion of the metal substratecomprises: feeding the powder coating composition to a transporter; anddirecting the powder coating composition from the transporter to atleast a portion of the metal substrate, by means of an electromagneticfield.
 18. The method of claim 12, wherein the chemically producedpowder polymer particles comprise a polymer selected from a polyacrylic,polyether, polyolefin, polyester, polyurethane, polycarbonate,polystyrene, or a combination thereof.
 19. The method of claim 12,wherein the hardened continuous adherent coating includes less than 50ppm of extractables, if any, when tested pursuant to a Global ExtractionTest using an extraction procedure conducted in accordance with the Foodand Drug Administration FDA “Preparation of Premarket Submission forFood Contact Substances: Chemistry Recommendations,” (December 2007),and exhibits an adhesion rating of 9 or 10 when tested pursuant to ASTMD 3359-17 (2017), Test Method B, Adhesion Test.
 20. The method of claim12, wherein the hardened continuous adherent coating has an averagethickness of up to 50 microns.
 21. The method of claim 12, wherein thechemically produced powder polymer particles have a particle sizedistribution having a D90 of less than 20 microns.
 22. The method ofclaim 12, wherein the chemically produced powder polymer particlescomprise agglomerates of primary polymer particles.
 23. A method ofmaking metal packaging, the method comprising: providing a metalsubstrate having a hardened continuous adherent coating disposed on atleast a portion of a surface thereof, wherein: the metal substrate hasan average thickness of up to 635 microns; and the hardened continuousadherent coating is formed from a metal packaging powder coatingcomposition; wherein the metal packaging powder coating compositioncomprises magnetic carrier particles and chemically produced powderpolymer particles; wherein the powder polymer particles comprise apolymer having a number average molecular weight of at least 2000Daltons, wherein the powder polymer particles have a particle sizedistribution having a D50 of less than 20 microns; and forming thesubstrate into at least a portion of a metal packaging container, aportion thereof, or a metal closure.
 24. The method of claim 23, whereinthe hardened continuous adherent coating disposed on at least a portionof a surface of the metal substrate does not include the magneticcarrier particles.
 25. The method of claim 23, wherein the chemicallyproduced powder polymer particles comprise a polymer selected from apolyacrylic, polyether, polyolefin, polyester, polyurethane,polycarbonate, polystyrene, or a combination thereof.
 26. The method ofclaim 23, wherein forming comprises forming the substrate into a rivetedcan end.
 27. The method of claim 23, wherein the chemically producedpowder polymer particles comprise agglomerates of primary polymerparticles.
 28. The method of claim 23, wherein the chemically producedpowder polymer particles are spray dried powder polymer particles.